The Sec15 protein responds to the function of the GTP binding protein, Sec4, to control vesicular traffic in yeast.
SEC15 function is required at a late stage of the yeast secretory pathway. Duplication of the gene encoding the ras-like, GTP-binding protein, Sec4, can suppress the partial loss of function resulting from the sec15-l mutation, but cannot suppress disruption of sec15. Analysis of the SEC15 gene predicts a hydrophilic protein product of 105 kD. Anti-Sec15 antibody recognizes a protein of 116-kD apparent molecular mass which is associated with a microsomal fraction of yeast in a strongly pH dependent fashion. Overproduction of Sec15 protein interferes with the secretory pathway, resulting in the formation of a cluster of secretory vesicles, and a patch of Sec15 protein revealed by immunofluorescence. The sec4-8 and sec2-4l mutations, but not mutations in other SEC genes, prevent formation of the Sec15 protein patch. We propose that Sec15 protein responds to the function of the Sec4 protein to control vesicular traffic.
Salminen
A
A
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Novick
P J
PJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005796:Genes; D005800:Genes, Fungal; D005838:Genotype; D008861:Microsomes / Q000378:metabolism; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D033921:Vesicular Transport Proteins
D004271:DNA, Fungal; C060862:SEC15 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D019204:GTP-Binding Proteins