MIMM 214 Lecture Notes - Lecture 19: Tapasin, Mhc Class Ii, Calnexin
10 Sep 2018
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Document Summary
6-4 mhc i are retained in the er until they bind peptide. If the supply of peptides into the er is disrupted, mhc i molecules are retained in the er, partially folded. Tap1 and tap2 human mutants have immunodeficiency and few mhc i on their cells. The folding and assembly of mhc i depends on association of mhc alpha chain with b2 microglobulin and peptide. This process involves accessory proteins that act like chaperones. When mhc i binds peptide, it is release from er and transported to cell surface. Newly-synthesised mhc i will bind calnexin in er. Retains the mhc i in a partly folded state. It also associated with partly-folded tcrs, igs and mhc ii. When b2-microglobulin binds to the alpha chain, partly-folded mhc i dissociates from calnexin and binds to complex of proteins called peptide-loading complex (plc) It forms a bridge between mhc i and tap.
