Abstract
We previously described the isolation of ysl2-1 due to its genetic interaction with Delta ypt51/vps21, a mutant with a deletion of the coding sequence for the yeast Rab5 homolog, which regulates endocytic traffic between early and late endosomes. Here we report that Ysl2p is a novel 186.8-kDa peripheral membrane protein homologous to members of the Sec7 family. We provide multiple genetic and biochemical evidence for an interaction between Ysl12p and the Arf-like protein Arl1p, consistent with a potential function as an Arf guanine nucleotide exchange factor (GEF). The temperature-sensitive alleles ysl2-307 and ysl2-316 are specifically defective in ligand-induced degradation of Ste2p and alpha-factor and exhibit vacuole fragmentation directly upon a shift to 37 degrees C. In living cells, green fluorescent protein (GFP)-Ysl2p colocalizes with endocytic elements that accumulate FM4-64. The GFP-Ysl2p staining is sensitive to a mutation in VPS27 resulting in the formation of an aberrant class E compartment, but it is not affected by a sec7 mutation. Consistent with the idea that Ysl2p and Arl1p have closely related functions, Delta arl1 cells are defective in endocytic transport and in vacuolar protein sorting.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
ADP-Ribosylation Factors*
-
Amino Acid Sequence
-
Base Sequence
-
Carboxypeptidases / metabolism
-
Cathepsin A
-
Endocytosis*
-
Endosomes / metabolism
-
Fluorescent Dyes / chemistry
-
Fungal Proteins / metabolism
-
GTP Phosphohydrolases / genetics
-
GTP Phosphohydrolases / metabolism*
-
Glycoside Hydrolases / metabolism
-
Green Fluorescent Proteins
-
Guanine Nucleotide Exchange Factors / metabolism*
-
Intracellular Membranes / metabolism
-
Luminescent Proteins / genetics
-
Luminescent Proteins / metabolism
-
Membrane Proteins / genetics
-
Membrane Proteins / metabolism*
-
Molecular Sequence Data
-
Mutation
-
Organic Anion Transporters, Sodium-Dependent / genetics
-
Organic Anion Transporters, Sodium-Dependent / metabolism*
-
Pyridinium Compounds / chemistry
-
Quaternary Ammonium Compounds / chemistry
-
Sequence Analysis
-
Sequence Homology, Amino Acid
-
Sodium-Coupled Vitamin C Transporters
-
Symporters*
-
Temperature
-
Vacuoles / metabolism
-
Vacuoles / ultrastructure*
-
beta-Fructofuranosidase
Substances
-
FM 4-64
-
Fluorescent Dyes
-
Fungal Proteins
-
Guanine Nucleotide Exchange Factors
-
Luminescent Proteins
-
Membrane Proteins
-
Organic Anion Transporters, Sodium-Dependent
-
Pyridinium Compounds
-
Quaternary Ammonium Compounds
-
Sec7 guanine nucleotide exchange factors
-
Sodium-Coupled Vitamin C Transporters
-
Symporters
-
Green Fluorescent Proteins
-
Glycoside Hydrolases
-
beta-Fructofuranosidase
-
Carboxypeptidases
-
Cathepsin A
-
ADP-ribosylation factor related proteins
-
GTP Phosphohydrolases
-
ADP-Ribosylation Factors