Definitions of J Chains

  1. The immunoglobulin fragments found in the light chain fractions of secretory IMMUNOGLOBULIN A and polymeric IMMUNOGLOBULIN M in a ratio of one J chain per one IMMUNOGLOBULIN A dimer or one IMMUNOGLOBULIN M pentamer. It is a polypeptide with a molecular weight of about 17 kD and probably serves either to bind the components of the globulins together or to transfer the globulins across membranes.