Figure 1

The zebrafish genome contains two complexin 3 orthologs and three complexin 4 orthologs. (A) The deduced amino acid sequences of mouse, human, and zebrafish complexins 3 and 4 are aligned with ClustalW. The shaded regions highlight evolutionarily conserved amino acids. Complexins 3 and 4 are highly homologous to each other (50 to 75% amino acid identity), but not to the complexin 1/2 subfamily (approximately 25% amino acid identity). Members of the complexin 3/4 subfamily share two motifs not present in the complexin 1/2 subfamily - a carboxy terminus prenylation motif (CAAX) and a putative bipartite nuclear localization signal (KKAERATVRSHFREKYRL in zebrafish complexin 3a). The GenBank accession numbers are: zf cplx 3a, [GenBank:GU174497]; zf cplx 3b, [GenBank:GU174498]; zf cplx 4a, [GenBank:GU174499]; zf cplx 4b, [GenBank:GU174500]; zf cplx 4c, [GenBank:GU174501]; hu cplx 3, [GenBank:NP_001025176]; hu cplx 4, [GenBank:NP_857637]; mo cplx 3, [GenBank:NP_666335]; mo cplx 4, [GenBank:NP_663468]. (B) An unrooted phylogram of vertebrate complexin 3 and 4 proteins was constructed with the neighbor joining method, and bootstrap values were calculated from 2,000 trials. Branch length is proportional to evolutionary divergence. Zebrafish complexins 3a and 3b segregate closely with mammalian complexin 3, and zebrafish complexins 4a and 4b segregate closely with mammalian complexin 4. A fifth paralog is designated zebrafish complexin 4c given its relatively closer distance to mammalian complexin 4 isoforms. Cplx, complexin; hu, human; mo, mouse; zf, zebrafish.