Marchalonis JJ ; Hohman VS ; Kaymaz H ; Schluter SF ; Edmundson AB ;

Ann N Y Acad Sci vol. 712   pp. 20-33, 15 Avr 1994

Department of Microbiology and Immunology, University of Arizona, College of Medicine, Tucson 85724.

Immunoglobulins serve as humoral recognition and effector molecules and as antigen-specific cell surface receptors on B and T cells. These molecules are constructed according to a characteristic domain pattern. Variable and constant domains diverged from one another early in vertebrate evolution, and they are joined by a 'switch peptide' specified by the joining gene segments. Peptides specified by J-gene segments are strongly conserved in evolution in comparison among Ig light chains and T-cell receptors. Molecules less strongly related to Ig domains have been assembled into an Ig 'superfamily' where the identities to classical IgC or V domains are < or = 20%. Among these are cell surface adhesion molecules, receptors for cytokines, and Fc receptors. Moreover, MHC antigens have an Ig-like membrane-proximal domain significantly related to IgC regions. We will analyze putative evolutionary relationships among canonical Igs and members of the Ig superfamily using highly conserved sequences from light and heavy chains of primitive vertebrates (e.g., the sandbar shark) as prototypes to ascertain similarities between Ig-related molecules of vertebrates and invertebrates.

Amino acid sequence ;  Animal ;  Cell Membrane: immunology ;  Conserved sequence ;  Evolution ;  Genes,Immunoglobulin ;  Human ;  Immunoglobulin Constant Region: genetics ;  Immunoglobulins: chemistry: genetics ;  Immunoglobulins,Light-Chain: chemistry: genetics ;  Immunoglobulins,lambda-Chain: chemistry: genetics ;  Models,Molecular ;  Molecular Sequence Data ;  Receptors,Antigen,T-Cell,alpha-beta: chemistry: genetics ;  Sequence Homology,Amino Acid ;  Sharks: genetics: immunology ;  Support,U.S.Gov't,Non-P.H.S. ;  Support,U.S.Gov't,P.H.S. ;  34230 ;