Symersky J, Novak J, McPherson D T, DeLucas L, Mestecky J
Center for Macromolecular Crystallography, University of Alabama at Birmingham, AL 35294, USA.
Mol Immunol. 2000 Feb-Mar;37(3-4):133-40. doi: 10.1016/s0161-5890(00)00035-3.
Selective transport of polymeric (p) immunoglobulins (Ig) of IgA and IgM isotypes into external secretions by pIg receptor-mediated mechanism depends on the incorporation of joining (J) chain into the polymers. Until now, availability of a free J chain for immunological and biophysical studies has been limited to preparations of denatured J chain forms with moderate yield. Here we report that a recombinant J chain (rJ) can be over-expressed as a soluble fusion protein with thioredoxin using a modified vector pET32 in Escherichia coli. An intact J chain was released by digestion with IgA1 protease from Neisseria gonorrhoeae and isolated in a good yield with immunological and biochemical properties similar to those of J chain obtained by chemical cleavage from pIgA.
