Unusual Association of β 2-microglobulin with Certain Class I Heavy Chains of the Murine Major Histocompatibility Complex

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 83; no. 2; pp. 432 - 436
• Main Authors: Bushkin, Yuri, Tung, Jwu-Sheng, Pinter, Abraham, Michaelson, James, Boyse, Edward A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.01.1986; National Acad Sciences
• Subjects: Alleles; Animals; Antiserum; beta 2-Microglobulin - genetics; beta 2-Microglobulin - metabolism; Biochemistry; Disulfides; Gels; H-2 Antigens - genetics; Immunogenetics; Leukemia; Macromolecular Substances; Major Histocompatibility Complex; Membrane Proteins - metabolism; Mice; Molecular Weight; Molecules; Product labeling; Structure-Activity Relationship; Transplantation immunology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.83.2.432

Class I products of the major histocompatibility complex (MHC) comprise a heavy chain of about 45 kDa noncovalently linked to a 12-kDa β 2-microglobulin (β 2m) light chain encoded on a different chromosome. We find that class I products of some mouse strains include an additional 62-kDa molecule which on the following evidence consists of a heavy chain linked covalently with β 2m. Production of the 62-kDa protein invariably accorded with the occurrence of cysteine at position 121 of the heavy chain (Kb, Kbm1, Kbm3, Dd, and Ld). Substitution of arginine at position 121 invariably accorded with absence of the 62-kDa protein (Kbm6, Kbm7, Kbm9, Kd, and Db). On the basis of observed production versus nonproduction of the 62-kDa molecule, predictions are made regarding residue 121 in class I products for which this is not yet known; namely, Kk, Ks, and Dk, which produce the 62-kDa molecule, as compared with Kj, Qa-2, and TL, which do not. Reported differences in immunologic reactivity between Kb mutant strains with Arg-121 in place of Cys-121 imply that the occurrence of 62-kDa class I products in mice of Cys-121 genotype has functional consequences.