The 21-kDa GTP-binding Ypt1 protein (Ypt1p) is required for protein transport from the endoplasmic reticulum to the Golgi complex in yeast extracts. Ypt1 antibodies block transport; this inhibition is alleviated by competition with excess purified Ypt1p produced in bacteria. Furthermore, extracts of cells carrying the mutation ypt1-1 are defective in transport, but transport is restored if a cytosolic fraction from wild-type cells is provided. The in vitro transport reaction also requires physiological levels of Ca2+. However, Ypt1p functions independently of Ca2+. First, buffering the free Ca2+ at concentrations ranging from 1 nM to 10 microM does not relieve inhibition by Ypt1 antibodies. Second, consumption of a Ca2+-requiring intermediate that accumulates in Ca2+-deficient incubations is not inhibited by anti-Ypt1 antibodies, although completion of transport requires ATP and an N-ethylmaleimide-sensitive factor. Thus, Ypt1p and Ca2+ are required at distinct steps.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|