ASSOCIATION OF THE HIGH-AFFINITY RECEPTOR FOR IGG (FC-GAMMA-RI) WITH THE GAMMA-SUBUNIT OF THE IGE RECEPTOR

How receptors for the Fc portion of IgG antibodies (FcgammaR) trigger a variety of immune functions by clustering upon engagement of ligand is largely unknown. Of the three distinct classes of human FcgammaR, only FcgammaRIIIA has been shown to associate with a potential signal-generating subunit, either the gamma chain or the zeta chain. With these studies we show that FcgammaRI, the high-affinity receptor for IgG, also is found in association with gamma chain. This association can be demonstrated by using anti-FcgammaRI antibodies, FcgammaRI ligand, and anti-gamma-chain antibodies that coadsorb the proteins from detergent lysates of FcgammaRI-expressing cells. The association of FcgammaRI and gamma chain can be reconstituted by cotransfection of cDNAs for both proteins into COS cells.