The genes of two G-proteins involved in protein transport in Pichia pastoris

Members of the Rab protein family play essential roles in vesicle fusion du ring protein secretion and represent highly conserved GTP binding proteins. The Saccharomyces cerevisiae Sec4p and Ypt1p, promoting vesicle fusion at the plasma membrane and in ERGolgi transport, respectively, are among the b est characterised yeast members. We have here cloned the Pichia pastoris SE C4 homologue using a S. cerevisiae SEC4 probe. In addition we isolated a cr osshybridising clone encoding another Rab-Npt-like protein. The deduced ful l-length PpSec4p comprises 204 amino acid residues with an over all identit y of 64% to the Sec4p from S. cerevisiae and 72% to the Candida albicans Se c4p. The YPT-like gene encodes a 216 amino acid residue protein showing hig hest similarity to the S. cerevisiae Ypt10p and Ypt53p. Both PpSec4p and th e Ypt-like protein carry a -Cys-Cys C-terminus, indicating that these prote ins are targets for geranylgeranylation by a type II prenyltransferase. (C) 2001 Academic Press.