Annals of the New York Academy of Sciences, Vol 712, Issue 1 20-33, Copyright © 1994 by New York Academy of Sciences
Cell surface recognition and the immunoglobulin superfamily
J. J. Marchalonis, V. S. Hohman, H. Kaymaz, S. F. Schluter and A. B. Edmundson
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.
