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Disparate interaction of peptide ligand with nascent versus mature class I major histocompatibility complex molecules: comparisons of peptide binding to alternative forms of Ld in cell lysates and the cell surface.
- Source :
-
The Journal of experimental medicine [J Exp Med] 1992 Jan 01; Vol. 175 (1), pp. 191-202. - Publication Year :
- 1992
-
Abstract
- To determine the mechanism and structural consequences of peptide binding to class I molecules, we have studied the Ld molecule of the mouse. Previous studies have shown that a significant proportion of surface and intracellular Ld molecules can be detected in an alternative conformation designated Ldalt. Ldalt molecules are non-ligand associated and show weak if any beta 2-microglobulin (beta 2m) association. We report here that Ld molecules have a relatively rapid surface turnover compared with other class I molecules and that exogenous peptide dramatically prolongs Ld surface half-life. By contrast, Ldalt molecules are stably expressed on the surface and their half-life is unaffected by exogenous peptide. To study the surface interaction of peptide with Ld, live cells were incubated with iodinated peptides and Ld molecules were precipitated from cells precoated with monoclonal antibody before lysis. Using this assay, peptide binding to surface Ld molecules was found not to depend upon exchange with exogenous beta 2m, but did correlate with the level of beta 2m association. To study the intracellular interaction of peptide with Ld, cell lysates were used. In cell lysates, peptide was found to convert Ldalt molecules to properly folded Ld. This peptide-induced folding was almost complete at earlier but not later time points in pulse-chase analyses. Furthermore, conversion of Ldalt to Ld was found to affect almost exclusively immature (Endo Hs) class I molecules. Thus intrinsic properties of immature Ldalt molecules or their associated chaperonins are maintained in cell lysates that allow them to undergo de novo folding in vitro. These combined results demonstrate that immature Ldalt molecules are precursors awaiting constituents such as peptide and beta 2m that influence folding, whereas surface Ldalt molecules appear refractory to association with peptide, beta 2m, and consequent folding.
- Subjects :
- Animals
Antibodies, Monoclonal
Cell Membrane immunology
Flow Cytometry
Histocompatibility Antigens analysis
Histocompatibility Antigens genetics
Histocompatibility Antigens Class I analysis
Kinetics
L Cells
Mice
Peptides chemical synthesis
Peptides immunology
Protein Binding
Transfection
beta 2-Microglobulin immunology
Histocompatibility Antigens immunology
Histocompatibility Antigens Class I immunology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-1007
- Volume :
- 175
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The Journal of experimental medicine
- Publication Type :
- Academic Journal
- Accession number :
- 1730917
- Full Text :
- https://doi.org/10.1084/jem.175.1.191