Immunoglobulin variable-region-like domains of diverse sequence within the major histocompatibility complex of the chicken.
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 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.
Miller
M M
MM
Department of Molecular Biochemistry, Beckman Research Institute, City of Hope Medical Center, Duarte, CA 91010-0269.
Goto
R
R
Young
S
S
Chirivella
J
J
Hawke
D
D
Miyada
C G
CG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D003488:Cyanogen Bromide; D004247:DNA / Q000235:genetics; D004912:Erythrocytes / Q000737:chemistry; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000235:genetics*; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D021382:Protein Sorting Signals; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D007135:Immunoglobulin Variable Region; D010446:Peptide Fragments; D021382:Protein Sorting Signals; D004247:DNA; D003488:Cyanogen Bromide