Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.52 (PNGase F)
 1,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human neutrophils constitutively express two low-affinity Fc gamma R, Fc gamma RII (CD32) and Fc gamma RIII (CD16). Eleven monoclonal antibodies (mAb) to CD16 were used to identify antigenic differences among Fc gamma RIII-bearing cells, to define functional epitopes of Fc gamma RIII on neutrophils, and to characterize biochemically the epitopes identified by some of these mAb. Flow cytometry demonstrated that 9 of the 11 mAb reacted with neutrophils, 10 of the 11 reacted with natural killer cells, and 9 of 11 reacted with monocytes and monocyte-derived macrophages. These mAb reacted with CD16 positive cells with varying fluorescence intensities. The ability of anti-CD16 mAb to block the binding of 125I-labeled immune complexes to neutrophils was examined. Four monoclonal antibodies strongly inhibited (87-96%) the binding to neutrophils of 125I-labeled immune complexes. Competitive binding assays were performed to determine whether any other anti-CD16 mAb identify the epitope identified by mAb 3G8. Two other mAb, CLBFCGRAN 1 and CLBGRAN 11, blocked binding of 125I-3G8 IgG to neutrophils. Six of the anti-CD16 mAb efficiently immunoprecipitated polypeptides of broad mobility ranging from 45 to 84 kDa from 125I-labeled neutrophils. When Fc gamma RIII, a complex sialoglycoprotein consisting of almost 50% oligosaccharides, was immunoprecipitated from neutrophils with 3G8 Fab Sepharose and subsequently digested with N-glycanase, 5 of the 6 mAb were capable of immunoprecipitating a deglycosylated polypeptide migrating at 29 kDa. These results demonstrate that these 5 mAb identify polypeptide epitopes of Fc gamma RIII, whereas 1 mAb, YFC120.5, may react with a glycosyl moiety or a determinant whose conformation is dependent on the presence of oligosaccharides.
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PMID:Monoclonal antibodies to human neutrophil Fc gamma RIII (CD16) identify polypeptide epitopes. 170 70

CD16 Ag is associated with the low affinity FcR for IgG expressed on human NK cells and granulocytes. In this study, we demonstrate that NK cells specifically lyse murine anti-CD16 hybridoma cell lines, but do not lyse hybridomas against other cell surface differentiation Ag expressed on NK cells. Moreover, the CD18 structure is involved in the CD16-specific xenogeneic interaction between human effector cells and murine hybridoma target cells. Although interaction with anti-CD16 hybridomas or antibodies triggers the cytolytic mechanism of NK cells, this interaction does not induce cellular proliferation. In contrast to NK cells, CD16+ granulocytes do not lyse anti-CD16 hybridoma cell targets and do not mediate ADCC against antibody-coated human tumor cell targets. These findings indicate a fundamental difference in the antibody-dependent cellular cytotoxicity mechanisms of NK cells and granulocytes. Comparative biochemical analysis of CD16 on NK cells and granulocytes revealed significant differences in the size of the polypeptides obtained after removal of N-linked carbohydrate residues with endo-F and N-glycanase digestion.
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PMID:Functional and biochemical analysis of CD16 antigen on natural killer cells and granulocytes. 290 93

Three types of receptor for the Fc (constant) region of human immunoglobulin G have been described; FcRI, a high-affinity (Ka approximately equal to 10(8) M-1) receptor expressed on monocytes; FcRII (CD32), a low-affinity (Ka approximately equal to 10(6) M-1) receptor expressed on B cells, granulocytes, macrophages and platelets; and FcRIII (CD16, FcRIo), a low-affinity receptor expressed on macrophages, neutrophils, eosinophils, natural killer cells and a subset of T cells believed to comprise the suppressor cells. Anti-CD16 antibodies block natural killer-cell mediated antibody dependent cellular cytotoxicity (ADCC). Binding of aggregated IgG to CD16 on natural killer cells leads to the expression of lymphocyte activation antigens, mediator release, morphological changes and lytic activity. We report here the isolation of a complementary DNA clone encoding CD16 determinants which gave rise to IgG binding of the expected affinity and subtype specificity in COS cells, and which proved to encode a phospholipid anchored protein. A single messenger RNA transcript was found in all positive RNA samples, and N-glycanase treatment showed the form found in COS cells was identical to the form present on peripheral blood mononuclear cells (PBMCs). We also show that CD16 is most closely related to the alpha-form of the murine IgG 2b/1 receptor and propose that extracellular contacts mediate the signal initiated by IgG binding.
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PMID:The Fc gamma receptor of natural killer cells is a phospholipid-linked membrane protein. 296 36