Primary structure of murine major histocompatibility complex alloantigens: Amino acid sequence studies of the cyanogen bromide fragments of the H-2K b glycoprotein

Abstract

Radiochemical microtechniques were used in the amino acid sequence analysis of 5 major CNBr [cyanogen bromide] fragments of the glycoprotein specified by the murine major histocompatibility complex gene H-2Kb. These fragments were tentatively aligned and represent the NH2-terminal 80% of the intact molecule. All amino acids except Asp, Asn, and Gln have been assigned in 128 of 149 possible positions in the NH2-terminal portions of each of these fragments. These assignments, which represent approximately 50% of the total sequence from these fragments, are listed below in the order of their alignment in the intact H-2Kb molecule: IIIn, -PHSLRYFVTAVSRP(G)L(G)(E)PRYM; IIIa, EVGYV-TEFVRF-S-AE(A)PRYEPRA(A).sbd.M; Ib, E-EGPEYWERET-KAK(G)-E-SFR.sbd.LRTLL(G)YY.sbd.TK; Ia, AALITK-KWE-AGEAERLRAYLEGTC-E-L; Ic, ELVETRPAG-GTF-KWAS-VVPLGKE-YY(T). The unassigned positions represented by dashes in the above sequences may be tentatively assigned as Asp, Asn or Gln. The NH2-terminal sequence obtained for the H-2Kb molecule was compared to the limited sequence information available for other major histocompatibility complex gene products. An 84% homology (16 of 19 residues) to the H-2Kq and H-2Kk molecules, which are identical to one another in the positions compared, was observed. A similar comparison with 28 of the 31 NH2-terminal residues of HLA-B7 indicated 68% homology. Significant homology was observed between H-Kb and HLA-B7 in a region of glycosylation, which occurs between positions 85 and 100 in the 2 molecules.