The yeast SLY gene products, suppressors of defects in the essential GTP-binding Ypt1 protein, may act in endoplasmic reticulum-to-Golgi transport.

AUTOR(ES)

Ossig, R

RESUMO

It has been shown previously that defects in the essential GTP-binding protein, Ypt1p, lead to a block in protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus in the yeast Saccharomyces cerevisiae. Here we report that four newly discovered suppressors of YPT1 deletion (SLY1-20, SLY2, SLY12, and SLY41) to a varying degree restore ER-to-Golgi transport defects in cells lacking Ypt1p. These suppressors also partially complement the sec21-1 and sec22-3 mutants which lead to a defect early in the secretory pathway. Sly1p-depleted cells, as well as a conditional lethal sly2 null mutant at nonpermissive temperatures, accumulate ER membranes and core-glycosylated invertase and carboxypeptidase Y. The sly2 null mutant under restrictive conditions (37 degrees C) can be rescued by the multicopy suppressor SLY12 and the single-copy suppressor SLY1-20, indicating that these three SLY genes functionally interact. Sly2p is shown to be an integral membrane protein.

Documentos Relacionados

• GTP-binding Ypt1 protein and Ca2+ function independently in a cell-free protein transport reaction.
• Nucleotide sequence of the mouse ypt1 gene encoding a ras-related GTP-binding protein.
• rsly1 Binding to Syntaxin 5 Is Required for Endoplasmic Reticulum-to-Golgi Transport but Does Not Promote SNARE Motif Accessibility
• Mutational analysis of the putative effector domain of the GTP-binding Ypt1 protein in yeast suggests specific regulation by a novel GAP activity.
• Potential Role for Protein Kinases in Regulation of Bidirectional Endoplasmic Reticulum-to-Golgi Transport Revealed by Protein Kinase Inhibitor H89