Kb, K(d), and L(d) molecules share common tapasin dependencies as determined using a novel epitope tag

N. B. Myers, M. R. Harris, J. M. Connolly, L. Lybarger, Y. Y.L. Yu, T. H. Hansen

Research output: Contribution to journalArticle

56 Scopus citations

Abstract

The endoplasmic reticulum protein tapasin is considered to be a class I-dedicated chaperone because it facilitates peptide loading by proposed mechanisms such as peptide editing, endoplasmic reticulum retention of nonpeptide-bound molecules, and/or localizing class I near the peptide source. Nonetheless, the primary functions of tapasin remain controversial as do the relative dependencies of different class I molecules on tapasin for optimal peptide loading and surface expression. Tapasin dependencies have been addressed in previous studies by transfecting different class I alleles into tapasin-deficient LCL721.220 cells and then monitoring surface expression and Ag presentation to T cells. Indeed, by these criteria, class I alleles have disparate tapasin-dependencies. In this study, we report a novel and more direct method of comparing tapasin dependency by monitoring the ratio of folded vs open forms of the different mouse class I heavy chains, L(d), K(d), and Kb. Furthermore, we determine the amount of de novo heavy chain synthesis required to attain comparable expression in the presence vs absence of tapasin. Our findings show that tapasin dramatically improves peptide loading of all three of these mouse molecules.

Original languageEnglish
Pages (from-to)5656-5663
Number of pages8
JournalJournal of Immunology
Volume165
Issue number10
DOIs
StatePublished - Nov 15 2000

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