Polymeric Immunoglobulin Receptor (PIGR)

Polymeric immunoglobulin receptor is a Fc receptor which facilitates the secretion of IgA and IgM. The poly-Ig receptor is expressed on several glandular epithelia including those of liver and breast. It mediates transcellular transport of polymeric immunoglobulin molecules.

It is a member of the immunoglobulin superfamily (Hood et al., 1985). The receptor has 5 units with homology to the variable (V) units of immunoglobulins and a transmembrane region, which also has some homology to certain immunoglobulin variable regions.