科研之友
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摘要
Unlike the human FcgammaRII and FcgammaRIII families, which exhibit considerable diversity at both the nucleic acid and protein levels, the human FcgammaRI family has only a single recognized product expressed as a 70-kD cell surface receptor with high affinity for monomeric IgG (hFcgammaRIa1). Using both polymerase chain reaction-based amplification and Northern hybridization, we document multiple interferon-gamma-inducible hFcgammaRI RNA transcripts in human mononuclear cells and neutrophils. The sequences of two of these FcgammaRI related transcripts indicate that they are alternatively spliced products of a second FcgammaRI family gene, termed FcgammaRIB. The cDNA derived from the larger of these transcripts, termed hFcgammaRIb1, encodes a surface molecule that is not recognized by FcgammaRI specific monoclonal antibodies when transfected into COS-7 cells. Unlike the interferon-gamma-inducible hFcgammaRIA gene product, hFcgammaRIb1 does not bind monomeric IgG with high affinity. However, both hFcgammaRIa1 and hFcgammaRIb1 do bind aggregated human IgG. Previously unrecognized diversity within the hFcgammaRI family includes an interferon-gamma-inducible, putative low affinity Fcgamma receptor that may play an important role in the mechanism by which Fcgamma receptors participate in the humoral immune response.
- 出版日期1992-11
