Yarrowia lipolytica SRP receptor alpha-subunit.

The Yarrowia lipolytica SRP101 homologue encoding the signal recognition particle (SRP) receptor alpha-subunit (SRalphap) was cloned using degenerate primers designed for conserved GTP-binding domains. Sequencing of 2814 nucleotides revealed an open reading frame of 1671 base pairs encoding a putative protein of 557 amino acids with a predicted molecular mass of 61 kDa. Like other SRP101 homologues, Y. lipolytica SRP101 contains a highly conserved C-terminal GTP binding site. It has 44%, 34% and 22% sequence identity with S. cerevisiae, mammalian and Escherichia coli homologues, respectively. As found for SRP protein subunits of Y. lipolytica, SRP101 is important but not essential for cell growth. A conditional mutation in SRP101 affected synthesis/translocation of alkaline extracellular protease and Kar2p consistent with Srp101p functioning as an SRP receptor subunit. The SRP101 sequence has been deposited in GenBank under Accession No. AF132597. Copyright 2000 John Wiley & Sons, Ltd.