Proteomic Identification of Common SCF Ubiquitin Ligase FBXO6-Interacting Glycoproteins in Three kinds of Cells

Abstract

FBOX6 ubiquitin ligase complex is involved in the endoplasmic reticulum-associated degradation pathway by mediating the ubiquitination of glycoproteins. FBXO6 interacts with the chitobiose in unfolded N-glycoprotein, pointing glycoproteins toward E2 for ubiquitination. Although the glycoprotein-recognizing mechanism of FBXO6 is well documented, its bona fide interacting glycoproteins are largely unknown. Here we utilized a protein purification approach combined with LC-MS to systematically identify the FBXO6-interacting glycoproteins. Following identification of 39 proteins that specifically interact with FBXO6 in all three different cell lines, 293T, HeLa and Jurkat cells, we compared the protein complex organization between wild-type FBXO6 and its mutant, which fails to recognize glycoproteins. Combining these databases, 29 highly confident glycoproteins that interact with FBXO6 in an N-glycan dependent manner are identified. Our data provide valuable information for the discovery of the interacting glycoproteins of FBXO6 and also demonstrate the potential of these approaches as general platforms for the global discovery of interacting glycoproteins of other FBAs (F-box associated regions) containing F-box proteins.