Ras-GAP SH3 domain binding protein (G3BP) is a modulator of USP10, a novel human ubiquitin specific protease.
Degradation of cellular proteins through ubiquitination is a fundamental strategy for regulating biological pathways. De-ubiquitination, i.e. the removal of ubiquitin from proteins and peptides to which ubiquitin is attached, is catalyzed by processing proteases known as de-ubiquitinating enzymes. We are studying the biology of a family of de-ubiquitinating enzymes, the mammalian ubiquitin-specific proteases (USPs), some of which appear to play a role in growth control. Given the fact that the modes of regulation of USPs and of their substrate specificity are poorly understood, we decided to attempt the identification of USP interacting proteins. Using the yeast two-hybrid system (2HS), we have isolated a cDNA clone whose product specifically interacts with USP10 but not with other USP baits tested. The isolated clone encodes a protein known to interact with the Ras-GTPase activating protein (G3BP). This interaction was further confirmed by performing a 2HS with G3BP, which led to the isolation of USP10 encoding cDNAs. We validated the interaction between the two proteins by performing in vitro binding assays and immunoprecipitations in human cells. G3BP does not appear to be a substrate of USP10; it rather inhibits the ability of USP10 to disassemble ubiquitin chains. The USP10/G3BP complex appears to co-immunoprecipitate with ubiquitinated species that could be substrates of USP10.
Soncini
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European Institute of Oncology, Department of Experimental Oncology, Via Ripamonti 435, 20141 Milan, Italy.
Berdo
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Draetta
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases; D018076:DNA, Complementary; D010450:Endopeptidases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D000075223:Poly-ADP-Ribose Binding Proteins; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins; D043222:Ubiquitin Thiolesterase; D014452:Ubiquitins / Q000378:metabolism*
D002352:Carrier Proteins; D018076:DNA, Complementary; D000075223:Poly-ADP-Ribose Binding Proteins; D000067776:RNA Recognition Motif Proteins; C431363:USP10 protein, human; D014452:Ubiquitins; D010450:Endopeptidases; D043222:Ubiquitin Thiolesterase; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases