Class I MHC molecules are ternary complexes composed of an allotype specific heavy chain, a noncovalently associated protein beta(2)-microglobulin (beta(2)m), and a peptide. The complexes are assembled in the endoplasmic reticulum by a complex series of chaperones and peptide-loading mechanisms. In the absence of beta(2)m or peptide, very little class I heavy chain is transported to the surface of the cell. Complexes that do not contain all three parts of the protein are not made productively in vivo and not at all in vitro. The ability of the complex to withstand thermal denaturation in vitro has been shown to be related to the binding affinity of the peptide. Paradoxically, some low-affinity peptide complexes denature at or below human basal body temperatures in vitro but are effective biological agents in vivo. Here we show that these complexes are stabilized against thermal denaturation by physiological cosolvents and maximally stabilized by 150 mM NaCl. While the degree of stabilization by 150 mM NaCl is greatest for low-affinity peptide/MHC complexes, the mechanism of stabilization is independent of peptide sequence. This effect is hypothesized to occur by multiple mechanisms including increasing the affinity of beta(2)m for the complex and charge screening. Study holds ProTherm entries: 8533, 8534, 8535, 8536, 8537, 8538, 8539, 8540, 8541, 8542, 8543, 8544, 8545, 8546, 8547, 8548, 8549, 8550, 8551, 8552, 8553, 8554, 8555, 8556, 8557, 8558 Extra Details: The peptide is IISAVVGIL chaperones; peptide-loading mechanisms; binding affinity;,peptide; charge screening
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:36 p.m.
|Number of data points||26|
|Proteins||H-2 class I histocompatibility antigen, D-B alpha chain ; Minor histocompatibility antigen H13 ; MHC class I polypeptide-related sequence A|
|Assays/Quantities/Protocols||Experimental Assay: Tm ionic:NaCl: 100 mM ; Experimental Assay: Tm ionic:NaCl: 150 mM ; Experimental Assay: Tm ionic:NaCl: 0.0 mM|
|Libraries||Mutations for sequence MGLGPVFLLLAGIFPFAPPGAAAEPHSLRYNLTVLSWDGSVQSGFLTEVHLDGQPFLRCDRQKCRAKPQGQWAEDVLGNKTWDRETRDLTGNGKDLRMTLAHIKDQKEGLHSLQEIRVCEIHEDNSTRSSQHFYYDGELFLSQNLETKEWTMPQSSRAQTLAMNVRNFLKEDAMKTKTHYHAMHADCLQELRRYLKSGVVLRRTVPPMVNVTRSEASEGNITVTCRASGFYPWNITLSWRQDGVSLSHDTQQWGDVLPDGNGTYQTWVATRICQGEEQRFTCYMEHSGNHSTHPVPSGKVLVLQSHWQTFHVSAVAAAAIFVIIIFYVRCCKKKTSAAEGPELVSLQVLDQHPVGTSDHRDATQLGFQPLMSDLGSTGSTEGA ; Mutations for sequence A:GPHSMRYFETAVSRPGLEEPRYISVGYVDNKEFVRFDSDAENPRYEPRAPWMEQEGPEYWERETQKAKGQEQWFRVSLRNLLGYYNQSAGGSHTLQQMSGCDLGSDWRLLRGYLQFAYEGRDYIALNEDLKTWTAADMAAQITRRKWEQSGAAEHYKAYLEGECVEWLHRYLKNGNATLLRTDSPKAHVTHHPRSKGEVTLRCWALGFYPADITLTWQLNGEELTQDMELVETRPAGDGTFQKWASVVVPLGKEQNYTCRVYHEGLPEPLTLRWE/B:IQKTPQIQVYSRHPPENGKPNILNCYVTQFHPPHIEIQMLKNGKKIPKVEMSDMSFSKDWSFYILAHTEFTPTETDTYACRVKHDSMAEPKTVYWDRDM/C:SSVVGVWYL|