Fig. 3

Aligning representative Vertebrata protein-coding exon borders of all five major families of the Gα subunit. The highly conserved exon border positions give insight into the evolutionary divisions of GNA- genes. All protein-coding exons are represented as boxes which correlate with the curated average exon size (introns removed). GNAI and GNAQ share many exon borders positions (black lines) and four split codons (not shown) suggesting a closer evolutionary relationship. GNAV also shares six exon border positions with GNAI and GNAQ; this suggests that Gαv family is related to Gαi and Gαq despite its gene presence in a limited number of species. All three genes share four exon borders positions with GNAS (not considering the alternatively spliced exon3 or the extended exon4 of GNAS found in Placentalia). The lack of shared exon borders between GNA12 and the other subfamilies suggests that GNA12 may have originated as a retro-gene which independently gained introns