Opsin evolution: transducins

Transducin Evolution

Opsins have expanded considerably in deuterostomes. That expansion was coupled in complex ways to an expansion in transducin genes that are the first step in relaying the initial photoreception event.

Curious evolutionary origins of alpha subunit multiplicity

The human genome contains 16 paralogous alpha, 5 beta, and 11 gamma subunits of heterotrimeric guanine nucleotide binding protein (G protein) though not all combinations occur and few are specifically relevent to opsins. Because opsins comprise only 1% of total GPCR served and non-imaging early diverging species such sea urchin already have vast repertoires of GPCR-- 979 of them -- and complex multiplicities of hetertrimeric G protein subunits (below), Darwin's question on independent origins of vision is very muddled by pre-existence of various subsystems that were later exapted.

The primary issue under discussion here is expansion of ciliary and imaging opsin genes during an era when signaling partner components were also increasing by different and not fully coordinated genetic mechanisms. A G protein alpha subunit can serve other GPCR in addition to opsins and a given opsin does not necessarily signal via a dedicated alpha subunit. Beta and gamma subunits of heterotrimeric G protein have still different temporal expansion histories, again with implications for opsins, but that complexity is considered only tangentially here as only the alpha subunit binds directly to opsins.

Consequently we do not expect nor find a 1:1 mapping over time as these gene families expanded by separate sequences of events, even though these proteins were manifestly co-evolving. Still, we would like to understand ancestral and contemporary opsin signaling because photoreception in isolation accomplishes nothing. That signaling can be described in part by its downstream small molecule and membrane channel components.

Cone and rod opsins have dedicated alpha subunits called Gt transducins that, like so much in vertebrate vision, are genes already established prior to lamprey divergence in its long and short photoreceptors. The situation is the same for the two gamma inhibitory subunits of cGMP phosphodiesterase PDE6 family ultimately activated by transducin but the alpha catalytic subunit appears to have not yet duplicated in lamprey.

For brevity, 'dating an event' is shorthand here for thoroughly examining paralog number and syntenic relations in relevent genome browsers (and ancillary data at GenBank) and taking simplest scenario compatible with the data, typically a short sequence of common genetic events such as tandom duplication and divergence. Dating is not quantitatively chronological but rather relative to consecutive divergence nodes of the deuterostome phylogenetic tree. Note hagfish and early chordate topology remain slightly equivocal. Lamprey contigs assemblies are often too short to hold complete genes much less reveal syntenic relations.

As future assemblies of certain incomplete but critical genomes (such as lamprey and shark) improve and as established knowledge of ancestral genetic events grows, these working hypotheses can be sharpened in their details or confidence, or even replaced. However no improvement can be expected today from pseudo-objective theories of maximal parsimony or likelihood that at best bury dubious curational assumptions in software code and at worst underperform common sense.

Curiously, the 16 alpha subunit paralogs in human include 5 deeply conserved tandem pairs on five separate chromosomes, for example cone transducin GNAT2 and GNAI3. That suggests some combination of multiple local tandem gene duplications coupled with segmental, whole chromosomal, or even whole genome duplication of pairs, as considered early on for 9 phototransduction gene classes. Note to minimize coincidental synteny, it is imperative to establish that gene relationships are ancestral by comparative genomics.

With gene order otherwise so scrambled by inversion and translocation, perhaps some functional constraint has kept these tandem pairs together (as with the LWS opsin locus control region). Yet upstream GNAT2 regulation does not seem physically or functionally appropriate to GNAI3. The five tandem pairs do not exhibit consistent strand orientations.

It is very implausible that these genes arose elsewhere and were brought together by chromosomal rearrangement. Consequently one member of the pair must be parental to the other. This relationship must trump gene trees that emerge from alignment tools (which can be thrown off by a rapidly evolving gene). If one member of a tandem pair retains ancestral function, the other may be rapidly pushed away in sequence space to develop a selective niche, meaning an excessive rate of divergence and consequent misclassification.

Four other alpha subunits (GNAL, GNAS, GNA12, and GNA13) are so distantly diverged that they have utility here only as basal outgroups. They appear to already have been established in placazoan and been immune to subsequent expansion and contraction.

The alpha subunit GNAZ is a functioning processed retrogene with one intron in novel location and phasing (meaning it could not have arisen from incomplete processing). The two events both date to lamprey stem. The gene is now on human chr22; the parent gene lies in the GNAI group with implications for its signaling mechanism. The gene is exceedingly conserved, over 95% identity human to lamprey despite a billion years of branch length. This could cause confusion on Oxford grids (which ignores exon structure) because with 16 paralogs there is a fair chance of a coincidental non-orthologous high-scoring match in a given chromosomal comparison, yet this gene obviously did not arise by 1R or 2R and indeed itself remains single copy despite dating to the supposed whole genome duplication era pre-lamprey.

Evolutionary history of vertebrate transducin genes

A great deal is known about structure/function relationships in Galpha subunits which is very helpful in understanding conserved regions observed in linear sequence alignments. That information is summarized in the two graphics below.

(to be continued)

Selected alpha subunit reference sequences

>GNAT2_homSap Homo sapiens (human) Gt cone 8 exons chr1:109,952,320 tandem GNAi3
0 MGSGASAEDKELAKRSKELEKKLQEDADKEAKTVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHQDGYSPEECLEFKAIIYGNVLQSILAIIRAMTTLGIDYAEPSCA 0
0 DDGRQLNNLADSIEEGTMPPELVEVIRRLWKDGGVQACFERAAEYQLNDSASY 2
1 YLNQLERITDPEYLPSEQDVLRSRVKTTGIIETKFSVKDLNFR 2
1 MFDVGGQRSERKKWIHCFEGVTCIIFCAALSAYDMVLVEDDEV 0
0 NRMHESLHLFNSICNHKFFAATSIVLFLNKKDLFEEKIKKVHLSICFPEYD 1
2 GNNSYDDAGNYIKSQFLDLNMRKDVKEIYSHMTCATDTQNVKFVFDAVTDIIIKENLKDCGLF* 0

>GNAI3_homSap Homo sapiens (human) Gi 8 exons chr1:109,916,342 tandem GNAT2 stimulatory K channels 
0 MGCTLSAEDKAAVERSKMIDRNLREDGEKAAKEVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEDGYSEDECKQYKVVVYSNTIQSIIAIIRAMGRLKIDFGEAARA 0
0 DDARQLFVLAGSAEEGVMTPELAGVIKRLWRDGGVQACFSRSREYQLNDSASY 2
1 YLNDLDRISQSNYIPTQQDVLRTRVKTTGIVETHFTFKDLYFK 2
1 MFDVGGQRSERKKWIHCFEGVTAIIFCVALSDYDLVLAEDEEM 0
0 NRMHESMKLFDSICNNKWFTETSIILFLNKKDLFEEKIKRSPLTICYPEYT 1
2 GSNTYEEAAAYIQCQFEDLNRRKDTKEIYTHFTCATDTKNVQFVFDAVTDVIIKNNLKECGLY* 0

>GNAT1_homSap Homo sapiens (human) Gt rod 8 exons chr3:50,206,500 tandem GNAi2 intervening +SLC38A3 inversion
0 MGAGASAEEKHSRELEKKLKEDAEKDARTVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHQDGYSLEECLEFIAIIYGNTLQSILAIVRAMTTLNIQYGDSARQ 0
0 DDARKLMHMADTIEEGTMPKEMSDIIQRLWKDSGIQACFERASEYQLNDSAGYY 2
1 LSDLERLVTPGYVPTEQDVLRSRVKTTGIIETQFSFKDLNFR 2
1 MFDVGGQRSERKKWIHCFEGVTCIIFIAALSAYDMVLVEDDEV 0
0 NRMHESLHLFNSICNHRYFATTSIVLFLNKKDVFFEKIKKAHLSICFPDYD 1
2 GPNTYEDAGNYIKVQFLELNMRRDVKEIYSHMTCATDTQNVKFVFDAVTDIIIKENLKDCGLF* 0

>GNAI2_homSap Homo sapiens (human) Gi 8 exons chr3:50,260,220 tandem GNAT1 beta-adrenergic cAMP-inhibiting response 
0 MGCTVSAEDKAAAERSKMIDKNLREDGEKAAREVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEDGYSEEECRQYRAVVYSNTIQSIMAIVKAMGNLQIDFADPSRA 0
0 DDARQLFALSCTAEEQGVLPDDLSGVIRRLWADHGVQACFGRSREYQLNDSAAY 2
1 YLNDLERIAQSDYIPTQQDVLRTRVKTTGIVETHFTFKDLHFK 2
1 MFDVGGQRSERKKWIHCFEGVTAIIFCVALSAYDLVLAEDEEM 0
0 NRMHESMKLFDSICNNKWFTDTSIILFLNKKDLFEEKITHSPLTICFPEYT 1
2 GANKYDEAASYIQSKFEDLNKRKDTKEIYTHFTCATDTKNVQFVFDAVTDVIIKNNLKDCGLF* 0

>GNAT3_homSap Homo sapiens (human) Gt 8 exons chr7:79,925,923 tandem GNAi1
0 MGSGISSESKESAKRSKELEKKLQEDAERDARTVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHKNGYSEQECMEFKAVIYSNTLQSILAIVKAMTTLGIDYVNPRSA 0
0 EDQRQLYAMANTLEDGGMTPQLAEVIKRLWRDPGIQACFERASEY 2
1 QLNDSAAYYLNDLDRITASGYVPNEQDVLHSRVKTTGIIETQFSFKDLHFR 2
1 MFDVGGQRSERKKWIHCFEGVTCIIFCAALSAYDMVLVEDEEV 0
0 NRMHESLHLFNSICNHKYFSTTSIVLFLNKKDIFQEKVTKVHLSICFPEYT 1
2 GPNTFEDAGNYIKNQFLDLNLKKEDKEIYSHMTCATDTQNVKFVFDAVTDIIIKENLKDCGLF* 0

>GNAI1_homSap Homo sapiens (human) Gi 8 exons chr7:79,644,368 tandem GNAT3 beta-adrenergic cAMP-inhibiting response 
0 MGCTLSAEDKAAVERSKMIDRNLREDGEKAAREVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEAGYSEEECKQYKAVVYSNTIQSIIAIIRAMGRLKIDFGDSARA 0
0 DDARQLFVLAGAAEEGFMTAELAGVIKRLWKDSGVQACFNRSREYQLNDSAAY 2
1 YLNDLDRIAQPNYIPTQQDVLRTRVKTTGIVETHFTFKDLHFK 2
1 MFDVGGQRSERKKWIHCFEGVTAIIFCVALSDYDLVLAEDEEM 0
0 NRMHESMKLFDSICNNKWFTDTSIILFLNKKDLFEEKIKKSPLTICYPEYA 1
2 GSNTYEEAAAYIQCQFEDLNKRKDTKEIYTHFTCATDTKNVQFVFDAVTDVIIKNNLKDCGLF* 0 

>GNAO1_homSap Homo sapiens (human) Go 8 exons chr16:54,861,182 not in tandem
0 MGCTLSAEERAALERSKAIEKNLKEDGISAAKDVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEDGFSGEDVKQYKPVVYSNTIQSLAAIVRAMDTLGIEYGDKERK 0
0 ADAKMVCDVVSRMEDTEPFSAELLSAMMRLWGDSGIQECFNRSREYQLNDSAKY 2
1 YLDSLDRIGAADYQPTEQDILRTRVKTTGIVETHFTFKNLHFR 2
1 LFDVGGQRSERKKWIHCFEDVTAIIFCVALSGYDQVLHEDETT 0
0 NRMHESLKLFDSICNNKWFTDTSIILFLNKKDIFEEKIKKSPLTICFPEYT 1
2 GPSAFTEAVAYIQAQYESKNKSAHKEIYTHVTCATDTNNIQFVFDAVTDVIIAKNLRGCGLY* 0

>GNAZ_homSap Homo sapiens (human) Gi 2 exons chr22:21,769,945 chicken/fish/Callo/lamp/no ciona/no branch/no urch too not tandem pertussis-insensitive balance cochlear dopamine serotonin
0 MGCRQSSEEKEAARRSRRIDRHLRSESQRQRREIKLLLLGTSNSGKSTIVKQMKIIHSGGFNLEACKEYKPLIIYNAIDSLTRIIRALAALRIDFHNPDRAYDAVQLFALTGPAESKGEI
TPELLGVMRRLWADPGAQACFSRSSEYHLEDNAAYYLNDLERIAAADYIPTVEDILRSRDMTTGIVENKFTFKELTFKMVDVGGQRSERKKWIHCFEGVTAIIFCVELSGYDLKLYEDNQT 0
0 SRMAESLRLFDSICNNNWFINTSLILFLNKKDLLAEKIRRIPLTICFPEYKGQNTYEEAAVYIQRQFEDLNRNKETKEIYSHFTCATDTSNIQFVFDAVTDVIIQNNLKYIGLC* 0

>GNAQ_homSap Homo sapiens (human) Gq 7 exons --tandem to GNA14 chr9:79,680,511 phospholipase C-beta melanopsin signaling 
0 MTLESIMACCLSEEAKEARRINDEIERQLRRDKRDARRELKLLLL 1
2 GTGESGKSTFIKQMRIIHGSGYSDEDKRGFTKLVYQNIFTAMQAMIRAMDTLKIPYKYEHNKA 2
1 HAQLVREVDVEKVSAFENPYVDAIKSLWNDPGIQECYDRRREYQLSDSTKY 2
1 YLNDLDRVADPAYLPTQQDVLRVRVPTTGIIEYPFDLQSVIFR 2
1 MVDVGGQRSERRKWIHCFENVTSIMFLVALSEYDQVLVESDNE 0
0 NRMEESKALFRTIITYPWFQNSSVILFLNKKDLLEEKIMYSHLVDYFPEYD 1
2 GPQRDAQAAREFILKMFVDLNPDSDKIIYSHFTCATDTENIRFVFAAVKDTILQLNLKEYNLV* 0

>GNA14_homSap Homo sapiens (human) Gq 7 exons --tandem to GNAQ chr9:79,340,705 phospholipase C-beta delta opioid receptors 
0 MAGCCCLSAEEKESQRISAEIERQLRRDKKDARRELKLLLL 1
2 GTGESGKSTFIKQMRIIHGSGYSDEDRKGFTKLVYQNIFTAMQAMIRAMDTLRIQYVCEQNKE 2
1 NAQIIREVEVDKVSMLSREQVEAIKQLWQDPGIQECYDRRREYQLSDSAKY 2
1 YLTDIDRIATPSFVPTQQDVLRVRVPTTGIIEYPFDLENIIFR 2
1 MVDVGGQRSERRKWIHCFESVTSIIFLVALSEYDQVLAECDNE 0
0 NRMEESKALFKTIITYPWFLNSSVILFLNKKDLLEEKIMYSHLISYFPEYT 1
2 GPKQDVRAARDFILKLYQDQNPDKEKVIYSHFTCATDTDNIRFVFAAVKDTILQLNLREFNLV* 0

>GNA11_homSap Homo sapiens (human) Gq 7 exons ++tandem to GNA15 chr19:3,058,931phospholipase C-beta ubiquitous 
0 MTLESMMACCLSDEVKESKRINAEIEKQLRRDKRDARRELKLLLL 1
2 GTGESGKSTFIKQMRIIHGAGYSEEDKRGFTKLVYQNIFTAMQAMIRAMETLKILYKYEQNKA 2
1 NALLIREVDVEKVTTFEHQYVSAIKTLWEDPGIQECYDRRREYQLSDSAKY 2
1 YLTDVDRIATLGYLPTQQDVLRVRVPTTGIIEYPFDLENIIFR 2
1 MVDVGGQRSERRKWIHCFENVTSIMFLVALSEYDQVLVESDNE 0
0 NRMEESKALFRTIITYPWFQNSSVILFLNKKDLLEDKILYSHLVDYFPEFD 1
2 GPQRDAQAAREFILKMFVDLNPDSDKIIYSHFTCATDTENIRFVFAAVKDTILQLNLKEYNLV* 0

>GNA15_homSap Homo sapiens (human) Gq 7 exons ++tandem to GNA11 chr19 3,100,978 phospholipase C-beta hematopoietic cells 6x faster 
0 MARSLTWRCCPWCLTEDEKAAARVDQEINRILLEQKKQDRGELKLLLL 1
2 GPGESGKSTFIKQMRIIHGAGYSEEERKGFRPLVYQNIFVSMRAMIEAMERLQIPFSRPESKHH 2
1 ASLVMSQDPYKVTTFEKRYAAAMQWLWRDAGIRAYYERRREFHLLDSAVY 2
1 YLSHLERITEEGYVPTAQDVLRSRMPTTGINEYCFSVQKTNLR 2
1 IVDVGGQKSERKKWIHCFENVIALIYLASLSEYDQCLEENNQE 0
0 NRMKESLALFGTILELPWFKSTSVILFLNKTDILEEKIPTSHLATYFPSFQ 1
2 GPKQDAEAAKRFILDMYTRMYTGCVDGPEGSKKGARSRRLFSHYTCATDTQNIRKVFKDVRDSVLARYLDEINLL* 0

>GNAL_homSap Homo sapiens (human) Gs 12 exons chr18:11,679,824 imprinted dopamine receptors D1 and D5 Golf alpha 
0 MGCLGGNSKTTEDQGVDEKERREANKKIEKQLQKERLAYKATHRQTHRLLLL 1
2 GAGESGKSTIVKQMRILHVNGFNPE 2
1 EKKQKILDIRKNVKDAIV 0
0 TIVSAMSTIIPPVPLANPENQFRSDYIKSIAPITDFEYSQ 0
0 EFFDHVKKLWDDEGVKACFERSNEYQLIDCAQY 2
1 FLERIDSVSLVDYTPTDQ 00 DLLRCRVLTSGIFETRFQVDKVNFH 2
1 MFDVGGQRDERRKWIQCFN 1
2 DVTAIIYVAACSSYNMVIREDNNTNRLRESLDLFESIWNNR 2
1 WLRTISIILFLNKQDMLAEKVLAGKSKIEDYFPEYANYTVPED 1
2 ATPDAGEDPKVTRAKFFIRDLFL 0
0 RISTATGDGKHYCYPHFTCAVDTENIRRVFNDCRDIIQRMHLKQYELL* 0

>GNAS_homSap Homo sapiens (human) Gs 13 exons complex imprinted expression
MRKEALEKRAQKRAEKKRSKLIDKQLQDEKMGYMCTHRLLLL 1
2 GAGESGKSTIVKQMRILHVNGFNGE 2
1 EKATKVQDIKNNLKEAIETIV 0
0 AAMSNLVPPVELANPENQFRVDYILSVMNVPDFDFPP 0
0 EFYEHAKALWEDEGVRACYERSNEYQLIDCAQY 2
1 FLDKIDVIKQADYVPSDQ 00 DLLRCRVLTSGIFETKFQVDKVNFH 2
1 MFDVGGQRDERRKWIQCFN 1
2 DVTAIIFVVASSSYNMVIREDNQTNRLQEALNLFKSIWNNR 2
1 WLRTISVILFLNKQDLLAEKVLAGKSKIEDYFPEFARYTTPED 1
2 ATPEPGEDPRVTRAKYFIRDEFLRIST 0
0 ASGDGRHYCYPHFTCAVDTENIRRVFNDCRDIIQRMHLRQYELL* 0

>GNA12_homSap Homo sapiens (human) G12 4 exons chr7:2,792,376 MDCK cell tight junction 
0 MSGVVRTLSRCLLPAEAGGARERRAGSGARDAEREARRRSRDIDALLARERRAVRRLVKILLLGAGESGKSTFLKQMRIIHGREFDQKALLEFRDTIFDNILK 0
0 GSRVLVDARDKLGIPWQYSENEKHGMFLMAFENKAGLPVEPATFQL 0
0 YVPALSALWRDSGIREAFSRRSEFQLGESVKYFLDNLDRIGQL 0
0 NYFPSKQDILLARKATKGIVEHDFVIKKIPFKMVDVGGQRSQRQKWFQCFDGITSILFMVSSSEYDQVLMEDRRTNRLVESMNIFETIVNNKL
FFNVSIILFLNKMDLLVEKVKTVSIKKHFPDFRGDPHRLEDVQRYLVQCFDRKRRNRSKPLFHHFTTAIDTENVRFVFHAVKDTILQENLKDIMLQ* 0

>GNA13_homSap Homo sapiens (human) G12 4 exons chr17:60,460,255
MADFLPSRSVLSVCFPGCLLTSGEAEQQRKSKEIDKCLSREKTYVKRLVKILLLGAGESGKSTFLKQMRIIHGQDFDQRAREEFRPTIYSNVIKGMRVLVDAREKLHIPWGDNSNQQHGDKMMSFDTRAPMAAQGMVETRVFLQYLPAIRALWADSGIQNAYDRRREFQLGESVKYFLDNLDKLGEPDYIPSQQDILLARRPTKGIHEYDFEIKNVPFKMVDVGGQRSERKRWFECFDSVTSILFLVSSSEFDQVLMEDRLTNRLTESLNIFETIVNNRVFSNVSIILFLNKTDLLEEKVQIVSIKDYFLEFEGDPHCLRDVQKFLVECFRNKRRDQQQKPLYHHFTTAINTENIRLVFRDVKDTILHDNLKQLMLQ* 0


>GNAQ7a_calMil Callorhinchus milii
TGESGKSTFIKQMRIIHGSGYTDEDKRGFTKLVYQNIFTAVQAMIRAMDTLKIQYKYDYNKV

>GNA147b_calMil Callorhinchus milii
TGESGKSTFIKQMRIIHGDGYSDEDRKCFTKLVYQNIFTAMQAMIKAMDTLRIQYKNGQN

>GNAI18a_calMil Callorhinchus milii 8th exon
GESGKSTFIKQMR 21 RIIHEDGYSEEECKQYKAVVYSNTIQSIIAIIRAMGRLKIDF

>8b_calMil Callorhinchus milii 8th exon
GESGKSTIVKQMK

>GNAT2term1_calMil Callorhinchus milii no GNAT3, no GNAi3 no evidence of tandems
GNNSFDDAGLYIKMQFLDLNMRKDVKEIYSHLTCATDTENVKFVFDAVTDIIIKENLKDCGLF*

>GNAT1_calMil Callorhinchus milii
GPNTYEDAGNYIKLQFLELNMRKDVKEIYAHMTCATDTKNVKFVFDAVTDIIIKENLKECGLF*

>GNAI1_calMil Callorhinchus milii
GSNTYEEAAAYIQCQFEDLNKRKDTKEIYTHFTCATDTKNVQFVFDAVTDVIIKNNLKDCGLF* 0

>GNAI2term4_calMil Callorhinchus milii
GANKYDEAAAYIQTKFEDLNKRKDTKEIYTHFTCATDTKHVQFVFDAVTDVIIKNNLKDCGLF* 0

>GNAZ_calMil Callorhinchus milii AAVX01066028 (97%) exon2
0 SRMAESLRLFDSICNNNWFINTSLILFLNKKDLLAEKIKRIPLTVCFPEYKGQNTYEEAAVYIQRQFEDLNRNKETKEIYSHFTCATDTSNIQFVFDAVTDVIIQNNLKYIGLC* 0

>GNAO1term6_calMil Callorhinchus milii
GPNSYEDAAAYIQAQFESKN RSPNKEIYCHLTCATDTNNIQVVFDAVTDIIIANNLRGCGLY* 0

>GNAZ_calMil Callorhinchus milii
0 SRMAESLRLFDSICNNNWFINTSLILFLNKKDLLAEKIKRIPLTVCFPEYKGQNTYEEAAVYIQRQFEDLNRNKETKEIYSHFTCATDTSNIQFVFDAVTDVIIQNNLKYIGLC* 0

>GNAT1_petMar Petromyzon marinus (lamprey) EU571208 short photoreceptor transducin-alpha subunit rod
MGSGASAEDKDQAKHSKELEKKLAEDAEKDARTVKLLLLGAGESGKSTIVKQMKIIHQSGYSIEECMEFIAIIYSNTLQSILAIVRAMGTLSIDFGDSARMD
DARQLQNLADSIDEGTMPQELYLIIKRLWTDSGIQVCFDRASEYQLNDSAEYYLTDIDRLVQPGYLPTEQDVLRSRVKTTGIIETQFSFKDLHFRMFDVGGQRSERKKWIHCFEGV
TCIIFCAALSAYDMVLVEDDEVNRMHESLHLFNSICNHRYFNATSIVLFLNKKDLFEVKVKKAHLSICFPDYDGPNTYDDAGNFIKLQFLDLNMRKESKEIYSHMTCATDTKNVKFVFDAVTDIIIKENLKDCGLF

>GNAT2_petMar Petromyzon marinus (lamprey) EU571207 long photoreceptor transducin-alpha subunit contig4334 cone short intron still 8 exons
MGSGASAEDKESAKHSKELEKKLAEDAEKEARTVKLLLLGAGESGKSTIVKQMKIIHKNGYSEAECLEFKAIIYSNTLQSILAIVRAMETFSIDYGDPARAA
DGRQLFNLADSLEEGSMPNELSAIIIRLWKDTGVQASFDRASEYQLNDSASYYLNDLDRLMNPSYLPNEQDVLRSRVKTTGIIEDSFCFKDLQFRMFDVGGQRSERKKWIHCFEGV
TCIIFCGALSAYDMVLVEDDEVNRMHESLHLFNSICNHRYFNDTSIVLFLNKKDLFEEKVKKVHLNICFPDYDGPNTFDDAGAYIKNQFLDLNLRKEAKEIYSHLTCATDTQNVKFVFDAVTDIIIKNNLKDCGLF

>GNAI1_petMar Petromyzon marinus (lamprey) 
MGCTLSTEDKAAVERSRMIDRNLREDGEKASREVKLLLLGASHT
GAGESGKSTIVKQMK IIHEAGYTEEECKQYKAVVYSNTIQSVIAIIRAMGNLRIDFGDAGRA
DDARQLFVLAGSAEDGLMTPELAQVIKRLWADPGVQACFRRAREYQLNDSAA
YLNDLERISQPSYVPTQQDVLRTRVKTTGIVETHFTFKDLHFK 
MFDVGGQRSERKKWIHCFEGVTAIIFCVALSAYDLVLAEDEEM
NRMHESMKLFDSICNNKWFIETSIILFLNKKDLFEEKVIRSPLTICYPEYTGS 
AGGNTYEEAAAYIQTQFENLNKRKESKEIYTHFTCATDTKNVQFVFDAVTDVIIKNNLKDCGLF* 0

>GNAI2_petMar Petromyzon marinus (lamprey) frag
GAGESGKSTIVKQMK 21 IIHEDGYSEDECKQYTAVVFSNAIQSIIAIIRAMGKLKIDFGDVSRA 
EDARQLFVLAGVAEE-GVMTPDLSEVIKRLWSDSGVQACFRRSREYQLNDSAA
YLNDLERISNLSYIPTQQDVLRTRVKTTGIVETHFTFKDLHFK
MFDVGGQRSERKKWIHCFEGVTAIIFCVALSAYDLVLAEDEE
NRMHESMKLFDSICNNKWFTETSIILFLNKKDLFEEKINKSPLFICFAEYFG

>GNAZ_petMar Petromyzon marinus (lamprey) frag exon1
RAYDAVQLFALTGPAESKGEISPELLAIMRRLWCDPGVQLCFGRSSEYHLEDNAAYYLGDLERIAAPGYVPTVEDILRSRDMTTGIVENRFTFKELTFKMVDVGGQRSERKKWIHCFEGVTAIIFCVELSGYDLKLYEDNLT 0

>GNAO1_braFlo Branchiostoma floridae (amphioxus) ABEP01019035 83% 8 exons
0 MGCTMSAEERAAIEKTKQIDKNLKEDGLVAAKDIKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEDGFTTDDMQQFKPVVYSNTIQSLTSILRAMEVLKVEYG 0
0 DAKMVFEVVQRMEDTEPFSPELLAAMKRLWTDKGVQECFSRANEYQLNDSAK 2
1 YLDDLDRLGADEYEPTEQDILRTRVKTTGIVETHFTFKNLNFR 2
1 LFDVGGQRSERKKWIHCFEDVTAIIFVAALSGYDLVLHEDETT 0
0 NRMHESLKLFDSICNNKWFTETSIILFLNKKDLFEEKITRSPLTMAFPEYT 1
2 PPGPNTYTEAAAYVQAQFESKNKSPNKEIYTHMTCATDTSNIQFVFDAVTDVIIANNLRGCGLY* 0

>GNAI1_braFlo Branchiostoma floridae (amphioxus) ABEP01040635 BW845279 mrna 91% still has 8th exon
0 MGCAISAEDKAAAERSKMIDKNLRADGEKAAREVKLLLL 1
2 GAGESGKSTIVKQMK 21 IIHEDGYSEEECMQYKAVVYSNTIQSLIAIIRAMGTLKIDFG 0
0 DDARQLFALASTAEEGEMTPELAGIMKRLWADGGVQACFGRSREYQLNDSASR 2
1 YLNSLDRLAAGGYVPTQQDVLRTRVKTTGIVETHFTFKDLHFK 2
1 MFDVGGQRSERKKWIHCFEGVTAIIFCVALSAYDLVLAEDEETVGR 0
0 NRMHESMKLFDSICNNKWFTETSIILFLNKKDLFEEKITKSPLTICYPEYT 1
2 GGSNTYEEAAAYIQMQFEDLNKRKETKEIYTHFTCATDTNNIQFVFDAVTDVIIKNNLKDCGLF* 0 

>GNAQ_braFlo Branchiostoma floridae (amphioxus) ABEP01058052 ABEP01054441 frag very high percent id 7 exons
1 MNKMACCLSEEAKEQKRINQEIEKQLRKDKRDARRELKLLLL 1
2 TGESGKSTFIKQMRIIHGAGYSDEDRRGYTKLVYQNIFMAMHSMIRAMDTLKIAYKNKENE 0
0   SVSTFEKEYVEAIQSLWEDAGIQECYDRRREYQLTDSAKY 2
1 YLSDLERIAQPDYLPTEQDVLRVRVPTTGIIEYPFDLDNVIFR 2
1 MVDVGGQRSERRKWIHCFENVTSIMFLVALSEYDQVLVESDNE 0
0 NRMEESKALFRTIITYPWFQNSSVILFLNKKDLLEEKIMYSHLVDYFPEFD 1
2 GPQRDAQAAREFILKMFVDLNPDSDKIIYSHFTCATDTENIRFVFAAVKDTILQLNLKEYNLV* 0 
>GNAS_braFlo Branchiostoma floridae (amphioxus) FE588508 mrna 73%
KILHQNSFDEQERRQKIADIKKNIRDAIITITGAMSTLTPPVPLADHTLQARVDY IQDVATQPEFSYPPEFYEHTELLWKDGGVQACYERSNEYQLIDCAQYFLDRVHVVKQPDY 
EPTDQDILRCRVLTSGIFETKFEVNDVKFHMFDVGGQRDERRKWIQCFNDVTAIIFVVACSSYNMVLREDPSQNRLREALDLFKSIWNNRWLRTISVILFLNKQDLLKQKV

>GNA12_braFlo Branchiostoma floridae (amphioxus) BW845279 ABEP01001798 74%
EYIPSKQDVLYARKATKGIVEHEFDIKGIPFLMVDVGGQRSQRQKWFQCFESVTSILFLVSSSEFDQVLMEDRKTNRLVESLNIFETIVNNKTFTEVSIILFLNKTDLLQDKVTYVSIKE
YFPEFPEMSDPHN-LTDVQNFILNLF-DAKRRERNKPLFHHFTTAVDTENIKFVFHAVKDTILQDNLKQLML

>GNA13_braFlo Branchiostoma floridae (amphioxus) BW845279 ABEP01001790 63%
QDIEQRQRSKQIDKMLAKEKVHLRRQVKILLLGAGESGKSTFLKQMRIIHGKDFDVEALKEYRPTVYNNIVKGMKVLVDAQRKLGIKMKEPSNELYCDQVMKFEGTIKIDTALF
LEYCPAIRALWSDAGIQEAWDRRREFQLVRNSSSYNLEYIPSKQDVLYARKATKGIVEHEFDIKGIPFLMVDVGGQRSQRQKWFQCFESVTSILFLVSSSEFDQVLMEDRKTNRLVESLNIFET
IVNNKTFTEVSIILFLNKTDLLQDKVTYVSIKEYFPEFPEMSDPHNLTDVQNFILNLFDAKRRERNKPLFHHFTTAVDTENIKFVFHAVKDTILQDNLKQLML

>GNAQ_strPur Strongylocentrotus purpuratus NM_001001475 PUBMED 15003628
MACCLSEEAKEQKRINQEIEKQLRKDKRDARRELKLLLLGTGESGKSTFIKQMRIIHGAGYTEEDRKTFTKLVYQNIFMAINAMIRAMDTLKIAYGDPTNEKKAQEVRLIDHETVTVFHEPYIGYVDCIWNDSGIQECYDRRREYQLTDSAKYYLSDLKR
ISDSNYIPTEQDVLRVRVPTTGIIEYPFDLDSIIFRMVDVGGQRSERRKWIHCFENVTSIMFLVALSEYDQLLVESDSENRMEESKALFRTIITYPWFQNSSVILFLNKKDLLEEK
IMHSHLVDYFPEFDGPSRDATAAREFILKMFVELNPDSDKIIYSHFTCATDTENIRFVFAAVKDTILQLNLKEYNLV

>GNAI_strPur Strongylocentrotus purpuratus NM_001001475 PUBMED 15003628 still has short 8th exon
MGCATSAEDKAAAERSKMIDRNLRLEGEKAAREVKLLLLGAGESGKSTIVKQMKIIHEEGYSEEDCRQYKPVVYSNTIQSMIAIIRAMGSLKIDFGDTERAD
DARQLFALAGQAEEGELSTELAAVMKRLWADSGVQACFSRSREYQLNDSASYYLNALDRLSAPGYIPTQQDVLRTRVKTTGIVETHFTFKELHFKMFDVGGQRSERKKWIHCFEGV
TAIIFCVALSAYDLVLAEDEEMNRMHESMKLFDSICNNKWFTETSIILFLNKKDLFEEKIQKSPLTICFPEYTGSNTYEEAAAYIQMQFEDLNKRKDQKEIYTHFTCATDTNNIQFVFDAVTDVIIKNNLKDCGLF

>GNAO1_strPur Strongylocentrotus purpuratus genomic approx
MGCAMSSEERESQERSKQIDKNLKEDGLQAARDVKLLLLG AGESGKSTIVKQMKIIHEEGFTAEDSKVYRPVVYSNLLQSMVSMLRAREKFETPFGEEEREDAQLVYDTVSKLQDSAPYSPSLTAAIQRLWTDSGLLEIFNRAREYQLNDSAK FLDNLDRIGSPDYLPNEQDILRTRVKTTGIVETHFTFKNLHFRFHLITCRLFDVGGQRSERKKWIHCFEDVTAIIFCVALSGYDQRLLEDDVTNRMQESLKLFDSI
CNNKWFTDTSIILFLNKKDLFEEKIQKSPLTICFQEYTGANEYLPAAGYIQLQFEALNKSTNKEIYTHMTCATDTTNIQFVFDAVTDTIIANNLRGCGLY

>GNAS_strPur Strongylocentrotus purpuratus NM_001001475 PUBMED 15003628
MGCFGNGLSSEEKDEEKKRKEANKKIEKQLQKDKQIYRATHRLLLLGAGESGKSTIVKQMRILHVDGFSPDERKKKIEDIRRNIRDAIITITGAMSTLSPPI
QLAEPQNQFRLDYIQDVSSSPDFDYPEEFWDHTKHLWIDAGVQGCYDRSHEYQLIDSAQYFLDRVDTIRRPDYAPDLQDILRCRVLTSGIFETKFQVDKVNFHMFDVGGQRDERRK
WIQCFNDVTAIIFVVACSSYNLVLREDPNQNRLRESLELFRSIWNNRWLRTISVILFLNKQDLLAEKVQAGRSKIEDYFSEYAMYTIPPDAATDTGEPEDVLRAKYFIRDEFLRISTASGDGRHYCYPHFTCAVDTENIRRVFDDCRDIIQRMHLRQYELL

>GNA12_strPur Strongylocentrotus purpuratus NM_001001475 PUBMED 15003628 located on cytoplasmic vesicles
MAGTLLTCCLTPTDKQALNHSKDIDKQLQRDKNYIRREVKVLLLGAGESGKSTFLKQMKIIHEQQFTDQEVKEFRNIIYGNIIKGMKVLADARDKLGIPWGD
SGNEKHAEFVMSFNTQAAQLEPPLFVQYVQPCVELWKDSGIQSAFDRRREFQLADSVKYFLDEIDRVGRKDYIPSLTDILHSRKATKAFQEHVIDIRNVPFRFVDVGGQRSQRQKW
FQCFESVTSILFLASSSEFDQVLMEDRITNRLLESCNIFDTIVNHKCFASISIILFLNKTDLLEEKIKHVSIKDYFPNFQGDPHSMNDVQNFILKMFDVRRRERGSKALFHYFTTAVDTNNIRYVFQAVRDTILQENLKRLMLQ

>GNAI1_triAdh Trichoplax adhaerens (placazoa) XM_002115978 77% homSap 71% GNAi2 still 8 exons +GNAI2_triAdh +GNAI1_triAdh
MGCAASAGDKVAAAKSKEIDKKIKSDAEKAAREVKLLLLGAGESGKSTIVKQMRIIHESGFSEEDRAQYKPVVFSNTMQSMAAIIRAMGVLRIEFGDKTS
LVGDARRLFEIMDAPGVQEFTPEIVSLLKRLWSDHGVQQCFSRSREYQLNDSAPYYLNSIDRLGKPEYIPSEQDVLRTRVKTTGIVETHFTFKDLHFKMF
DVGGQRSERKKWIHCFEGVTAIIFCVSLSAYDLVLAEDEEMNRMMESMKLFDSICNNKWFTETSIILFLNKKDLFQEKILKSPLTICFPEYTGANTYEEA
SAYIQMKFEDLNKMKDQKEIYTHFTCATDTNNIQFVFDAVTDVIIKNNLKDCGLF*

>GNAI2_triAdh Trichoplax adhaerens (placazoa) XM_002115977 70% homSap 56% GNAi3
MGCLVSKDERAAAERSKIIDKNLKASGDVSAKEVKLLLLGAGESGKSTIVKQMRIIHEKGYSEQDCVQYRPVVYNNTVQSLATIIRACGPLGIPFENPSL
KDLSKEYFSMIERQGDSVELSKKLLTLMKTIWADNGIQESFKRSREYQLNDSAGYYLNDIDRLGTSNYIPTQQDVLRTRVKTTGIVETQFSFRDFRFKMV
DVGGQRSERKKWIHCFEGVTAIIFCVSLSAYDLKLAEDEEMNRMVESMRLFDSICNNQFFEETSIILFLNKKDLFQQKIAVSPLTLCFPEYSGANNYQEA
SSYIQTVFEDLNRKKESKEIYTHFTCATDTDNIQFVFDAVTDVIIKNNLKDCGLF*

>GNAI3_triAdh Trichoplax adhaerens (placazoa) XM_002116075 60% homSap 61% GNAi1
MGITVSGEDKAAREKSTDIDKKIQNEKDKSLSEVKLLLLGAGESGKSTIAKQMRIIHESGYSDEDRQQYKSIIHCNAIYSLKAIIEAMKVLKIDISRSHT
KIDAEDFLRLIYDSPDEVTPELKKIMKRLWNDPDVQKCFNRSREYQLMDSASYYLDDLDRLVQDSYLPSEQDILRARVKTSSIKETEFEYKGLEFKMIDV
GGQRSERRKWIHCFENVTAVIFCAALSAYDLVLQEDYFTNRMKESLNLFDSVCNNQWFKKTSIILFLNKTDIFKEKIRKSPITTCFPEYNGTNSYEETTS
YIQKKFISLNSNGKEKTIYSHFTCATDTENIVFVFAAVTDVILQKNIKEHGLLF*

>GNAO1_triAdh Trichoplax adhaerens (placazoa) XM_002111534 53% homSap 51% GNAi1
MGCGSSTVDQKAVIANNQIEKDIREQELQAKKIIKLLLLGAAESGKSTIAKQLKIIHMEGFTKNDIEKAKPIIYSNIVHTFIQILQNMRPLKLEFNSEQR
QADANQLFDIIGKMKDTDPYPPSVLKSMNALLADGGFQTTIKRGHEYHLHDSAEYFLKSLDRIGNDNYEPTEQDILRSRLRTTGVNQIEFEFKMLNFQVI
DVGGQRSERRKWIHVFDSVTAIIFCVSLSCYDMTVYEDGNTNSMHESLKLFDWIVNNEFFKETSIILFLNKKDLFEEKIKSVSLTVCFPEYDGTKSYEDT
SLFIQKQFIDRKQSSQKEIYCHLTCATDTQNISVVFDAVTDIVISNNLRNCGLL*

>GNAQ_triAdh Trichoplax adhaerens (placazoa) XM_002116172 76% homSap 48% GNAi3
MACCLSDEAREQRRINREIEKELKKHKRDAKRELKLLLLGTGESGKSTFIKQMRIIHGKGYTDNDRAEFTQLVFQNIFTAIQALIKAMETLNITYEHQSN
RQRVDVVRTVDPETVGSLSKEHVEAIDSIWNDSGVQECYDRRREYQLSDSAKYYLTDLHRLAEPNYLPTQQDILRVRAPTTGIIEYDFNLDTVMFRMVDV
GGQRSERRKWIHCFENVTSIMFLVALSEYDQILAEADSQNRMEESKALFKTIITYPWFQNSSIILFLNKKDILEEKVQKSNIADYFPEYDGPPRDAQAGR
EFILKMFVDLNPDSEKIIYSHFTCATDTENIRFVFAAVKDTILQFNLREYNLV*

>GNAS_triAdh Trichoplax adhaerens (placazoa) XM_002116172 74% homSap 44% GNAQ
MGCFGNQTEDSRLQKKENTRIERQLKKDKAAYRSTHRLLLLGAGESGKSTIVKQMRILHVDGFNEEEKRQKIADIKRNIRDSIVAIVTAMGTLTPPCTLANL
NNQFRVDYITEIASADDFNYPPVFFEHTKELWKDQGVQQCYERSNEYQLIDCAKYFLDKIDVVKLPDYQPTDQDVLRCRVLTSGIVETRFQVERVNFHMFDVGGQRDERRKWIQCF
NDVTAIIFVVACSSYNLVLREDPSQNRLKESLELFQTIWNNRWLKTISIILFLNKQDLLAEKVRAGRSKIEDYFSEFSRYTTPTDATTEPGDDENVKRAKYFIRDAFLRISTATGE
GKHYCYPHFTCAVDTENIRRVFNDCRDIIQRMHLRQYELL*

>GNA12_triAdh Trichoplax adhaerens (placazoa) XM_002116172 51% homSap 48% GNA13
MKRRNSKLIDKELSKEKKSRGRQIKILLLGAGESGKSTFLKQMRIIHGEEYSQKDLMEFKNLIYGNVVKNMRVLITARDSLGIKWANADYEDYAQELLAIDT
KSTVFDYAAFMSYAGKVVDLWQDRAIQQTYDKRNLYQLSDSTYYFMDRMKSLMDKAYVPTKQDVLRSRKATTNIVELTLNINRVPFTFVDVGGQRSQRRKWLQCFEGVTSVLFLVS
SCAYDQVLLEDNRTNRIVESCQIFDTIINNKFFAKVAIILFFNKTDILIEKVSLVSIKDYFPEFSRDPKKIEDVKHFLITMFEKVSNDQKRGLYHHFTTATDTENIKFVFNAVREM
ILEENMSILMLQ*

>GNA13_triAdh Trichoplax adhaerens (placazoa) XM_002109597 48% homSap 39% GNAQ
MDTVLCFKANSERREQIRHSKIIDQEILQERTEYYKTIKILLLGASECGKSTFLKQMRILHGQDFDVQDLLEFRSIIYGNIIRIMKVLVTARRSFEIQWKDS
SHQNYADQILNFNTKVNEIEPHEFVAVVDMIRELWLDEAIQETYRRRNEYILADSTKYFMDRLEVIGKEDYVPIRKDALRMRKATKTIVEFTTTINKIPFVFIDVGGQRSQRRKWL
QCFESITAILFLAAASDYNQVSLEDRKTNRLLESLEIFGAIVNHELLAKASKILFLNKIDLLEERLTISNIKNFFSAFNGDENDLTTVKEFILQLFSNKMEANNDNDKSLYHHYTI
ATDTENIKVVFRDVKQTILQERLGSLLLH*

>GNAI_monBre Monosiga brevicollis 3 exons no short XM_001747738 
0 MGICMSAEQKAQQARTAAVEAQLERDAQLASRTIKLLLL 1
2 GAGESGKSTLVKQMKIIHGDGFSNEELKSYKPTICDNLVHSMRAVLEAMGPLVIDIGDQVRPP 0
0 HAKVVLSYIELGTSGGLTPELTEALKALWADSGVQECFRRSNEYQLNDSAEYFFNNIDRIAQSNYLPTQEDVLRARVRTTGV
IETTFRYKDLIYRMFDVGGQRSERRKWIHCFNDVTAVLFVAALSGYDMKLFEDQETNRIHESLTLFDAICNNSFFINTAIILFL
NKTDLFSQKIARTPLKDYFPEYDGPPNNASEAKKFIAGMFKRLNKNPNKPVYEHFVCATETQNIRYVFDAVK* 0

>GNAQ_monBre Monosiga brevicollis no short XM_001745795 55% GNAQ_homSap
0 MPCGPPDETRRRSLAIDRQLRKERMSKQREYKILLL GTGESGKSTIIKQMRIIYGQGFNESDRLAYKPLVYRNIITSMKRMLDALDQLSLQLADSSLEEDAYDK
LDVDVNTVDAIEPYYPLLKKLWNDNGIQQVFQRRNEYQLSDSTAYYYNRLDAVAAADYIPTVDDVLRSRQATTGIHEFEFDLDSVVFRMMDVGGQRSERRKWIHSFE 0
0 GVTSIIFIAACNEYDQVLAEDTNVNRMQESLALFGQIIQYHW 2
1 FANSSFILFLNKQDLLEEKVKTHPIKPFFPDYTGQE 0
0 GDYENIKKFIETMYRSRKPAGKDLYTHFTMATDTSNIQFVFNAVRSTLLRIHLKDYNLF* 0