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)

P-glycoprotein (P-gp) is expressed in various non-cancerous tissues such as the endothelial cells of the blood-brain barrier. We used several monoclonal antibodies (mAbs) and isoform-specific polyclonal antibodies to establish which P-gp isoforms are expressed in isolated mouse brain capillaries. P-gp class I isoform was detected in capillaries with a Western immunoblotting procedure using a specific antiserum. No immunoreactivity was observed with either class II- or class III-specific antisera. Immunoreactivity was observed with mAb C219. However, this antibody detected two distinct immunoreactive proteins (155 and 190 kDa) in the isolated brain capillaries. These two proteins comigrated as a broad band when the samples were submitted to heat prior to gel electrophoresis. The glycoprotein nature of these two antigens was evaluated by their sensitivity to N-glycanase treatment. Following this treatment, the size of the proteins was reduced from 190 and 155 kDa to 180 and 120 kDa, respectively. Triton X-114 phase-partitioning studies showed that the 190 kDa immunoreactive protein was poorly solubilized by Triton X-114, while the 155 kDa protein was partitioned in the detergent-rich phase. In labelling experiments, only the 155 kDa protein was photolabelled with [125I]iodoarylazidoprazosin. These results show that a 190 kDa protein detected by antibody C219 is an antigen unrelated to the three P-gp isoforms presently known. Cross-reactivity of C219 with an unrelated protein emphasizes the fact that more than one antibody should be used in the assessment of P-gp expression in cell lines and tissues.
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PMID:Isoform I (mdr3) is the major form of P-glycoprotein expressed in mouse brain capillaries. Evidence for cross-reactivity of antibody C219 with an unrelated protein. 784 74

In order to study the membrane topology, processing, and oligomerization of inositol trisphosphate receptor (IP3R) isoforms, we have utilized RNA templates encoding putative transmembrane domains to program a cell-free translation system of rabbit reticulocyte lysates supplemented with canine pancreas microsomes. In the absence of microsomes, translation of the RNA templates encoding all the putative transmembrane domains present in the C-terminal segment of the type I (1TM) and type III (3TM) IP3R isoforms resulted in a 62- and 59-kDa polypeptide, respectively. In both cases, an additional band approximately 3 kDa larger was observed upon the addition of microsomes. Both bands in the translation doublet were integrated into microsomal membranes and were full-length translation products, as shown by sedimentation through a sucrose cushion and immunoprecipitation with C-terminal isoform-specific antibodies. With both isoforms, N-glycopeptidase F digestion indicates that the upper band in the doublet corresponds to a glycosylated translation product. A 17-kDa protected fragment was observed after proteinase-K digestion of 1TM translated in the presence of microsomes. The pattern and size of protected fragments was consistent with the current six-transmembrane domain model of IP3R topology. Cotranslation of both 1TM and 3TM RNA templates in the presence of microsomes followed by immunoprecipitation with isoform specific antibodies revealed coimmunoprecipitation of translation products. This was not observed when the isoforms were translated separately and then mixed, suggesting that heteroligomerization occurs cotranslationally. A construct encoding only the first putative transmembrane domain of the type I isoform was found to be sufficient for integration into membranes but was unable to oligomerize with either 1TM or 3TM. Cotranslation experiments using additional constructs indicate that the major structural determinant for homoligomerization lies between putative transmembrane domain 5 and the C terminus. A second oligomerization domain involved in stabilization of heteroligomers is present within the first four transmembrane domains.
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PMID:Membrane insertion, glycosylation, and oligomerization of inositol trisphosphate receptors in a cell-free translation system. 899 31