Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
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

Human Fc gamma RIII (CD16), a low-affinity receptor expressed on several different cell types, has a polymorphism on polymorphonuclear cells (Fc gamma RIIIPMN) identified by the NA1 and NA2 markers. Inasmuch as this polymorphism has functional consequences, an understanding of the structural biology of Fc gamma RIII may provide important insight into receptor function. We analyzed Fc gamma RIIIPMN by SDS-PAGE and found that receptor from individuals allotyped for either NA1 or NA2 contained only one protein after removal of N-linked glycosylations (19 and 21 kDa respectively) whereas receptor from NA1/2 individuals contained both bands. Because some reports indicate that digestion of Fc gamma RIII on NK cells (Fc gamma RIIINK) with N-glycanase also results in two bands on SDS-PAGE, we investigated Fc gamma RIIINK to explore the possibility of a corresponding allelic polymorphism in this receptor. Contrary to expectation, Fc gamma RIIINK from all donors irrespective of their NA allotype contained two bands (20 and 24 kDa) on SDS-PAGE after deglycosylation. In addition, those distinct epitopes on the extracellular domain of Fc gamma RIIIPMN found with mAb B73.1 and CLB gran 11 in association with the NA allotypic differences are expressed (or not expressed) on Fc gamma RIIINK independent of donor NA allotype. Fc gamma RIIIPMN and Fc gamma RIIINK differ at the protein level as they have different m.w. (glycosylated and deglycosylated), different epitopes in the extracellular domain (not attributable to tissue-specific glycosylation), and differential expression of the NA allelic protein polymorphism. Although the membrane anchor of Fc gamma RIIIPMN is a phosphatidylinositol-specific phospholipase C sensitive glycosyl-phosphatidylinositol linkage, Fc gamma RIIINK is insensitive to phosphatidylinositol-specific phospholipase C. However, a form of Fc gamma RIIINK is released from NK cells upon incubation at 37 degrees C. Thus, the basis for the two bands in Fc gamma RIIINK after N-linked deglycosylation is neither coexpression of two molecular isoforms with different membrane anchors nor an identifiable allelic polymorphism in m.w. restricted to Fc gamma RIIINK (p less than 10(-6)). The differences between the two receptors indicate that, independent of cell anchor type, PMN and mononuclear cells must have different molecular isoforms. The allelic variants, different isoforms, alternative anchor mechanisms and release processes provide for an extensive genetic and regulatory diversity in Fc gamma RIII function.
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PMID:Human Fc gamma RIII (CD16). Isoforms with distinct allelic expression, extracellular domains, and membrane linkages on polymorphonuclear and natural killer cells. 247 7

Two polymorphic forms of Fc receptor III (FcR III) are expressed on human neutrophils. These differ with respect to their apparent molecular masses after digestion with N-glycanase, and with respect to their reactivity with MAb Gran 11 and alloantisera which recognize determinants (NA1 and NA2) of the biallelic neutrophil antigen (NA) system. To determine the molecular basis for this polymorphism we isolated RNA from neutrophils of NA1NA1 and NA2NA2 homozygotes and synthesized corresponding cDNAs. cDNAs encoding FcR III were then amplified using the polymerase chain reaction, cloned, and sequenced. The cDNA that encodes FcR III on NA1NA1 neutrophils differed from the cDNA that encodes FcR III on NA2NA2 neutrophils at five nucleotides, predicting four amino acid substitutions. As a result, NA1 FcR III has only four potential N-linked glycosylation sites as compared with six in NA2 FcR III. The amino acid substitutions and differences in the number of potential N-linked glycosylation sites probably account for the different forms of neutrophil FcR III observed after digestion with N-glycanase and for the antigenic heterogeneity of this receptor.
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PMID:Sequences of complementary DNAs that encode the NA1 and NA2 forms of Fc receptor III on human neutrophils. 247 90

We characterized Fc receptor III (FcR III) on human neutrophils and found it to be heavily glycosylated and polymorphic. In some individuals, FcR III that had been digested with N-glycanase appeared after SDS-PAGE under reducing conditions as two bands with apparent molecular masses of 33 and 29 kD. In other individuals, N-glycanase-treated FcR III appeared as a single band with an Mr of either 33 or 29 kD. After SDS-PAGE of N-glycanase-treated FcR III under nonreducing conditions, the apparent Mr of each structural type was decreased, suggesting the presence of intramolecular disulfide bonds. Digestion of the 33-kD band and the 29-kD band with Staphylococcus aureus V8 protease yielded similar, but not identical, peptide maps. Thus, at least two polymorphic forms of FcR III are expressed on human neutrophils. The structural polymorphism of neutrophil FcR III correlated with previously described antigenic polymorphisms detected by monoclonal antibody Gran 11 and by alloantisera which recognize epitopes of the biallelic, neutrophil antigen (NA) system. Individuals whose neutrophils expressed the two-band structural type of FcR III were NA1NA2 heterozygotes. Individuals whose neutrophils expressed the single 33-kD band structural type were NA2NA2 homozygotes, and individuals whose neutrophils expressed the single 29-kD band structural type were NA1NA1 homozygotes. These findings indicate that antigenic and structural polymorphisms of human neutrophil FcR III are related and can be accounted for by differences at the level of primary protein structure.
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PMID:Characterization of polymorphic forms of Fc receptor III on human neutrophils. 252 15