Functional Studies on Components of the Secretory Pathway of 'Saccharomyces211 cerevisiae'

摘要

SSO genes have been isolated as multicopy suppressors of sec1-1, a mutation in a211u001elate-acting SEC gene causing accumulation of post-Golgi vesicles at the 211u001erestrictive temperature, and shown to encode the so-called target membrane SNAP 211u001ereceptors (t-SNAREs) in the plasma membrane of the yeast Saccharomyces 211u001ecerevisiae. The Sso proteins are type II membrane proteins that are capable of 211u001eposttranslational membrane insertion independent of signal recognition particals 211u001e(SRPs). Thus, they might be inserted to the plasma membrane directly instead of 211u001eentering the endoplasmic reticulum (ER) and being transported to their site of 211u001eaction along the biosynthetic pathway. The initial membrane insertion site of 211u001eSso2p in the secretory pathway was studied by transient expression of Sso2p in 211u001eanmal cells, which are superior to yeast for such morphological studies. Ss2p was 211u001eshown to be first inserted into the ER and then transported to the plasma 211u001emembrane via the secretory pathway.