5opi

Publication Abstract from PubMed

Adaptive immunity is shaped by a selection of peptides presented on major histocompatibility complex class I (MHC I) molecules. The chaperones Tapasin (Tsn) and TAP-binding protein-related (TAPBPR) facilitate MHC I peptide loading and high-affinity epitope selection. Despite the pivotal role of Tsn and TAPBPR in controlling the hierarchical immune response, their catalytic mechanism remains unknown. Here, we present the X-ray structure of the TAPBPR-MHC I complex, which delineates the central step of catalysis. TAPBPR functions as peptide selector by remodeling the MHC I alpha2-1-helix region, stabilizing the empty binding groove, and inserting a loop into the groove that interferes with peptide binding. The complex explains how mutations in MHC I-specific chaperones cause defects in antigen processing and suggests a unifying mechanism of peptide proofreading.

Structure of the TAPBPR-MHC I complex defines the mechanism of peptide loading and editing.,Thomas C, Tampe R Science. 2017 Oct 12. pii: eaao6001. doi: 10.1126/science.aao6001. PMID:29025996^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.