Immunoglobulin variable-region-like domains of diverse sequence within the major histocompatibility complex of the chicken

• Published in: Proceedings of the National Academy of Sciences - PNAS 1991-05, Vol.88 (10), p.4377-4381
• Main Authors: Miller, M.M. (Beckman Research Institute, Duarte, CA), Goto, R, Young, S, Chirivella, J, Hawke, D, Miyada, C.G
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; ANTIGENE; ANTIGENOS; Antigens; AVES DE CORRAL; Base Sequence; Biological and medical sciences; Chick Embryo; Chickens - genetics; CODE GENETIQUE; CODIGO GENETICO; Complementary DNA; Cyanogen Bromide; DNA - genetics; Erythrocytes; Erythrocytes - chemistry; Erythroid cells; Fundamental and applied biological sciences. Psychology; GENE; GENES; Genes, MHC Class I; Genes, MHC Class II; Genes. Genome; GENETICA; GENETIQUE; GROUPE SANGUIN; GRUPOS SANGUINEOS; Haplotypes; Immunogenetics; Immunoglobulin Variable Region - chemistry; Immunoglobulin Variable Region - genetics; IMMUNOGLOBULINE; Immunoglobulins; INMUNOGLOBULINA; Introns; Major Histocompatibility Complex; Major histocompatibility complex genes; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; NUCLEOTIDE; NUCLEOTIDOS; Peptide Fragments - chemistry; Polymorphism, Genetic; Protein Conformation; Protein Sorting Signals; Restriction Mapping; Sequence Homology, Nucleic Acid; SISTEMA MHC; SYSTEME MHC; VOLAILLE
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.10.4377

The highly polymorphic B-G antigens are considered to be part of the major histocompatibility complex (MHC) of the chicken, the B system of histocompatibility, because they are encoded in a family of genes tightly linked with the genes encoding MHC class I and class II antigens. To better understand these unusual MHC antigens, full-length B-G cDNA clones were isolated from a B21 embryonic erythroid cell cDNA library, restriction-mapped, and sequenced. Five transcript types were identified. Analysis of the deduced amino acid sequences suggests that the B-G polypeptides are composed of single extracellular domains that resemble immunoglobulin domains of the variable-region (V) type, single membrane-spanning domains typical of integral membrane proteins, and long cytoplasmic tails. Sequence diversity among the five transcript types was found in all domains, notably including the B-G immunoglobulin V-like domains. The cytoplasmic tails of the B-G antigens are made up entirely of units of seven amino acid residues (heptads) that are typical of an alpha-helical coiled-coil conformation. The heptads vary in number and sequence between the different transcripts. The presence within B-G polypeptides of polymorphic immunoglobulin V-like domains warrants further investigations to determine the degree and nature of variability within this domain in these unusual MHC antigens