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Cell. 1996 Jan 26;84(2):277-87.

Ubiquitination of a yeast plasma membrane receptor signals its ligand-stimulated endocytosis.

Author information

1
Department of Biochemistry, Biozentrum, University of Basel, Switzerland.

Abstract

Binding of alpha factor to Ste2p, a G protein-coupled plasma membrane receptor, activates a signal transduction pathway and stimulates endocytosis of the receptor-ligand complex. Ligand binding also induces ubiquitination of the Ste2p cytoplasmic tail. Protein ubiquitination is required for stimulated endocytosis of Ste2p, as internalization is 5- to 15-fold slower in ubc mutants that lack multiple ubiquitin-conjugating enzymes. In a C-terminal truncated form of Ste2p that is rapidly ubiquitinated and endocytosed in response to ligand binding, a single lysine to arginine substitution in its cytoplasmic tail eliminates both ubiquitination and internalization. Thus, ubiquitination of Ste2p itself is required for ligand-stimulated endocytosis. We propose that ubiquitination mediates degradation of receptor-ligand complexes, not via the proteasome, but by acting as a signal for endocytosis leading to subsequent degradation in the lysosome/vacuole.

PMID:
8565073
DOI:
10.1016/s0092-8674(00)80982-4
[Indexed for MEDLINE]
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