Human Fc gamma RIII: cloning, expression, and identification of the chromosomal locus of two Fc receptors for IgG.

Abstract

A cDNA clone encoding a human receptor for the Fc portion of IgG (Fc.gamma.R), Fc.gamma.RIII or CD16, was isolated from a human leukocyte library by a transient expression-immunoselection procedure. This cDNA (pGP5) encodes a 46-kDa phosphatidylinositol-linked cell surface protein with CD16 determinants and affnity for human IgG. The deduced protein sequence is most homologous to the murine receptor Fc.gamma.RII.alpha., with slightly less homology to the human receptors Fc.gamma.RII and Fc.epsilon.RI. The cDNA hybridizes to a 2.2 kilobase mRNA in human leukocytes and a cloned human natural killer cell line. Fc.gamma.RIII is mapped to chromosome 1 by spot-blot analysis of sorted human chromosomes. Hybridization of Fc.gamma.RII and Fc.gamma.RIII probes to restriction digests of human genomic DNA separated by pulsed by pulsed-field gel electrophoresis demonstrates physical linkage of the two genes within a maximum distance of 200 kilobases. The results identify a locus for at least two Fc.gamma.R genes on human chromosome I.