hamster monoclonal IgG; MHC class Ib Antibody (130) is an IgG Armenian hamster monoclonal MHC class Ib antibody (also designated MHC class I-b antigen M3 antibody, M3 histocompatibility (H) antigen antibody, or M3 N-formylated peptide specific MHC class 1b antibody) that detects the MHC class Ib protein of mouse and rat origin by IP and IF. MHC class Ib Antibody (130) is available as both the non-conjugated anti-MHC class Ib antibody form, as well as multiple conjugated forms of anti-MHC class Ib antibody, including PE, FITC. Major histocompatibility complex (MHC) molecules, also designated human leukocyte antigen (HLA) molecules, are cell-surface receptors that bind foreign peptides and present them to T lymphocytes. MHC class I molecules consist of two polypeptide chains, an a or heavy chain, and β-2-Microglobulin, a non-covalently associated protein. Cytotoxic T lymphocytes bind antigenic peptides presented by MHC class I molecules. Antigens that bind to MHC class I molecules are typically 8-10 residues in length and are stabilized in a peptide binding groove. MHC class II molecules are encoded by polymorphic MHC genes and consist of a non-covalent complex of an a and b chain. Helper T lymphocytes bind antigenic peptides presented by MHC class II molecules. MHC class II molecules bind 13-18 amino acid antigenic peptides. Accumulating in endosomal/lysosomal compartments and on the surface of B cells, HLA-DM and -DO molecules regulate binding of exogenous peptides to class II molecules (HLA-DR) by sustaining a conformation that favors peptide exchange. The differential structural properties of MHC class I and class II molecules account for their respective roles in activating different populations of T lymphocytes.