Biological inferences from IgM binding characteristics of recombinant human secretory component mutants.

The polymeric immunoglobulin receptor (pIgR) or membrane secretory component (SC) selectively transports polymeric IgA and IgM across secretory epithelial cells to mucosal surfaces. The ligand binding ectodomain consists of five homologous Ig-like domains with domain I being an absolute requirement for binding. The role of DII to V in IgM binding remains unknown.

In vitro refolding of recombinant human free secretory component using equilibrium gradient dialysis.

Human secretory component (SC) is associated with secretory immunoglobulins (IgA and IgM) and serves to protect the immunoglobulin in the harsh mucosal environment. SC is derived from the polymeric immunoglobulin receptor (pIgR) which transports polymeric immunoglobulins across epithelial cells into secretions. In this present study, we describe the first cloning, expression, in vitro refolding and purification of a free form of human secretory component (rSC) containing the five functional ligand binding domains using Escherichia coli BL21 (DE3).