Evolutionary hypervariability in the hinge region of the immunoglobulin alpha gene.
The hinge region of the immunoglobulin molecule is responsible for antigen-binding and cross-linking reactions, varying the distance between the two antigen-binding sites. As the amino acid sequence of the hinge region is identical among immunoglobulin molecules of the same (sub)class, it has been regarded as a constant region. By comparison of the nucleotide sequences among primate C alpha genes, it is clear that there is a wide variety of length among the hinge regions of hominoid C alpha genes, which basically consist of tandem repeats of a 15 base-pair sequence. This reiterated structure probably facilitates rapid evolutionary changes in the length of the hinge region. The hinge region of the Old World monkey C alpha gene has a non-reiterated structure whose nucleotide sequence is quite different from those of the hominoid C alpha genes, although its surrounding region is conserved during evolution. This unusual hypervariability reveals that the hinge region has evolved as a semi-variable region in contrast to its constant character from an ontogenic viewpoint.
Kawamura
S
S
Department of Anthropology, Faculty of Science, University of Tokyo, Japan.
Omoto
K
K
Ueda
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D005803:Genes, Immunoglobulin; D015186:Hominidae / Q000235:genetics*; D006801:Humans; D007137:Immunoglobulin alpha-Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D011323:Primates / Q000235:genetics*; D011487:Protein Conformation
D007137:Immunoglobulin alpha-Chains