The Evolution of the Immune Response VIII. Structural Studies of the Lamprey Immunoglobulin

TLDR: The observations presented show that the lamprey immunoglobulin lacks counterparts of heavy and light chains and does not possess interchain disulfide linkages between its major subunits.

Abstract: Highly purified preparations of radiolabeled lamprey immunoglobulin have been employed to study the structure of the immunoglobulin of this primitive vertebrate. The identity of the labeled material with that of the native immunoglobulin has been established. The lamprey immunoglobulin appears to be unique among vertebrate immunoglobulins since it has a unique molecular weight, electrophoretic mobility, and sedimentation velocity. It is also extremely labile and dissociates in solvents in a complex manner. The observations presented show that this molecule lacks counterparts of heavy and light chains and does not possess interchain disulfide linkages between its major subunits. A structural model based on its dissociation behavior is presented and the implications of such a structure in terms of molecular function and phylogenetic development are discussed.