Members of the Rab protein family play essential roles in vesicle fusion during protein secretion and represent highly conserved GTP binding proteins. The Saccharomyces cerevisiae Sec4p and Ypt1p, promoting vesicle fusion at the plasma membrane and in ER-Golgi transport, respectively, are among the best characterised yeast members. We have here cloned the Pichia pastoris SEC4 homologue using a S. cerevisiae SEC4 probe. In addition we isolated a crosshybridising clone encoding another Rab-/Ypt-like protein. The deduced full-length PpSec4p comprises 204 amino acid residues with an over all identity of 64% to the Sec4p from S. cerevisiae and 72% to the Candida albicans Sec4p. The YPT-like gene encodes a 216 amino acid residue protein showing highest similarity to the S. cerevisiae Ypt10p and Ypt53p. Both PpSec4p and the Ypt-like protein carry a -Cys-Cys C-terminus, indicating that these proteins are targets for geranyl-geranylation by a type II prenyltransferase.
Copyright 2001 Academic Press.