Antibody Structure: Amino Terminal Sequences of Nurse Shark Light and Heavy Chains

Abstract

The amino terminal 28 residues of light (L) and heavy (H) chains from nurse shark antibody of restricted heterogeneity to streptococcal group A variant carbohydrate are presented. The variable (V) regions of the nurse shark appear to be more closely related to mammalian κ than to mammalian λ chains. The V regions of nurse shark H chains (V_H regions) are more closely related to V_H regions of mammals than to their own V_L regions, suggesting that V_L and V_H genes had diverged before the divergence of the elasmobranch and mammalian evolutionary lines approximately 400 million years ago. The V regions of the nurse shark are approximately as divergent from mammalian V regions as the V regions of differing subgroups within a species are from one another.