Fc gamma RIII expressed on cultured monocytes is a N-glycosylated transmembrane protein distinct from Fc gamma RIII expressed on natural killer cells.

Abstract

Fc gamma RIII is a family of protein isoforms encoded by at least two distinct, yet highly homologous, genes. Fc gamma RIII on neutrophils is a glycosylphosphatidylinositol-linked protein with an allelic polymorphism (NA1/NA2) while Fc gamma RIII on NK cells (Fc gamma RIIINK) is an exclusively transmembrane protein without the NA polymorphism. The relationship of the isoform of Fc gamma RIII expressed on cultured monocytes (Fc gamma RIIIM phi) to these two forms, however, is unclear because some evidence suggests lowered expression of Fc gamma RIIIM phi in paroxysmal nocturnal hemoglobinuria (unlike Fc gamma RIIINK) and a unique deglycosylated m.w. for Fc gamma RIIIM phi. In this study we demonstrate that, as with Fc gamma RIIINK, Fc gamma RIIIM phi is resistant to the action of phosphatidylinositol-specific phospholipase C and is expressed at normal levels on affected (glycosylphosphatidylinositol-anchor negative) cultured monocytes from patients with paroxysmal nocturnal hemoglobinuria. Fc gamma RIIIM phi is also shed from the cell surface upon incubation at 37 degrees C. However, Fc gamma RIIIM phi and Fc gamma RIIINK have different m.w. as glycosylated proteins despite the same deglycosylated m.w. Thus, each cell type appears to express distinct glycoforms. These differences in glycosylation may influence the functional properties of the receptor.

• Authors: J C Edberg, M Barinsky, P B Redecha, J E Salmon, R P Kimberly
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 144 Issue 12 Pg. 4729-34 (Jun 15 1990) ISSN: 0022-1767 [Print] United States
• PMID: 2141043 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antigens, Differentiation
• Antigens, Surface
• Membrane Glycoproteins
• Receptors, Fc
• Receptors, IgG

Topics

• Antigens, Differentiation (classification, immunology, metabolism)
• Antigens, Surface (analysis)
• Cells, Cultured
• Flow Cytometry
• Glycosylation
• Humans
• Killer Cells, Natural (metabolism)
• Macrophages (immunology, metabolism)
• Membrane Glycoproteins (metabolism)
• Monocytes (metabolism)
• Precipitin Tests
• Receptors, Fc (classification, immunology, metabolism)
• Receptors, IgG