A comparison of the amino acid sequences of the extracellular domains of the immunoglobulin superfamily. Possible correlations between conservancy and conformation.

Amino acid sequences of immunoglobulins, histocompatibility antigens, Thy-1 antigens, polyimmunoglobulin receptor and T-lymphocyte receptor have been compared and conserved residues correlated with features on the atomic models of immunoglobulin fragments. The peptide chains are apparently folded into globular domains closely related in three-dimensional structure to immunoglobulin V or C domains. Exceptions are histocompatibility class I alpha 2 and class II beta 1 domains, distantly related, and class I and II alpha 1 domains, no apparent relationship to immunoglobulin domains.