Neerincx A, Hermann C, Antrobus R, van Hateren A, Cao H, Trautwein N, Stevanović S, Elliott T, Deane JE, Boyle LH. TAPBPR bridges UDP-glucose:glycoprotein glucosyltransferase 1 onto MHC class I to provide quality control in the antigen presentation pathway.
eLife 2017;
6:e23049. [PMID:
28425917 PMCID:
PMC5441866 DOI:
10.7554/elife.23049]
[Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 04/14/2017] [Indexed: 11/24/2022] Open
Abstract
Recently, we revealed that TAPBPR is a peptide exchange catalyst that is important for optimal peptide selection by MHC class I molecules. Here, we asked whether any other co-factors associate with TAPBPR, which would explain its effect on peptide selection. We identify an interaction between TAPBPR and UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1), a folding sensor in the calnexin/calreticulin quality control cycle that is known to regenerate the Glc1Man9GlcNAc2 moiety on glycoproteins. Our results suggest the formation of a multimeric complex, dependent on a conserved cysteine at position 94 in TAPBPR, in which TAPBPR promotes the association of UGT1 with peptide-receptive MHC class I molecules. We reveal that the interaction between TAPBPR and UGT1 facilities the reglucosylation of the glycan on MHC class I molecules, promoting their recognition by calreticulin. Our results suggest that in addition to being a peptide editor, TAPBPR improves peptide optimisation by promoting peptide-receptive MHC class I molecules to associate with the peptide-loading complex.
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