Post-translational transport of proteins into microsomal membranes of Candida maltosa.

We have isolated from the yeast Candida maltosa microsomal membranes that are active in the translocation of proteins synthesized in cell-free systems derived from C. maltosa, Saccharomyces cerevisiae or wheat germ. Translocation and core glycosylation of prepro-alpha-factor, a secretory protein, were observed with yeast microsomes added during or after translation. The signal peptide is cleaved off. Cytochrome P-450 from C. maltosa, the first integral membrane protein studied in a yeast system, is also inserted both co- and post-translationally into Candida microsomal membranes. Its insertion into canine microsomes occurs efficiently only in a co-translational manner and is dependent on the function of the signal recognition particle.