The SecY protein family: comparative analysis and phylogenetic relationships.

We have cloned and sequenced the plastome encoded secY homologue of the cryptomonad alga Pyrenomonas salina. In this study we have carried out a comparative analysis of all but one fully sequenced proteins of the SecY family. We present an alignment of 16 SecY family proteins, containing family signatures, putative transmembrane domains, consensus sequence, and conservation grade. A phylogenetic tree derived from the conserved blocks of the alignment reveals the relationships among this protein family. The tree shows division into two broad subfamilies, one consisting of prokaryotic and plastidal sequences and the other of eukaryotic as well as archaeal sequences.