A novel route for F-box protein-mediated ubiquitination links CHIP to glycoprotein quality control.

In SCF (Skp1/Cullin/F-box protein) ubiquitin ligases, substrate specificity is conferred by a diverse array of F-box proteins. Only in fully assembled SCF complexes, it is believed, can substrates bound to F-box proteins become ubiquitinated. Here we show that Fbx2, a brain-enriched F-box protein implicated in the ubiquitination of glycoproteins discarded ...
from the endoplasmic reticulum, binds the co-chaperone/ubiquitin ligase CHIP (C terminus of Hsc-70-interacting protein) through a unique N-terminal PEST domain in Fbx2. CHIP facilitates the ubiquitination and degradation of Fbx2-bound glycoproteins, including unassembled NMDA receptor subunits. These findings indicate that CHIP acts with Fbx2 in a novel ubiquitination pathway that links CHIP to glycoprotein quality control in neurons. In addition, they expand the repertoire of pathways by which F-box proteins can regulate ubiquitination and suggest a new role for PEST domains as a protein interaction motif.
Mesh Terms:
Amino Acid Sequence, Animals, Base Sequence, Binding Sites, COS Cells, Cercopithecus aethiops, DNA Primers, Drosophila Proteins, Glycoproteins, Glycosylation, Humans, Kinetics, Molecular Sequence Data, Neurons, Nuclear Proteins, Recombinant Fusion Proteins, SKP Cullin F-Box Protein Ligases, Transfection, Ubiquitin
J. Biol. Chem.
Date: Jul. 21, 2006
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