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

---

Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sequence information was obtained from low picomole amounts of nonspecific cross-reacting antigen (NCA) 160 (M(r) 160,000), a granulocyte membrane glycoprotein. Following affinity purification and SDS-polyacrylamide gel electrophoresis, the protein was electrotransferred to nitrocellulose, digested with trypsin, and the peptides were isolated using capillary reversed-phase liquid chromatography. Analysis of these peptides by Edman microsequencing and mass spectrometry established that NCA-160 was identical to biliary glycoprotein I, a protein that we previously cloned from a human colon library (1). NCA-160 from human granulocytes is a CD15-positive glycoprotein belonging to the carcinoembryonic antigen family and possesses putative transmembrane and cytoplasmic domains. Previous efforts to characterize this antigen at the protein level were hampered by a blocked NH2 terminus. In this study, we confirmed 20% of the deduced amino acid sequence starting with approximately 50 pmol of sample. Carbohydrate structural data is also presented on a single N-linked oligosaccharide moiety located in the A' domain. The capillary high performance liquid chromatography techniques used here, as well as mass spectrometry, were essential for high sensitivity analysis of the blotted, digested glycoprotein.
...
PMID:Microsequence and mass spectral analysis of nonspecific cross-reacting antigen 160, a CD15-positive neutrophil membrane glycoprotein. Demonstration of identity with biliary glycoprotein. 809 7

Agrin is a component of the synaptic basal lamina that induces the aggregation of acetylcholine receptors (AChRs) and other elements of the postsynaptic membrane. We have determined the localization, binding characteristics, and biochemical profile of the agrin receptor in Torpedo electric organ membranes and defined domains of agrin that bind this receptor. Postsynaptic membranes from Torpedo electric organ bind agrin as judged by depletion of AChR clustering activity from solution. A ligand-based radioimmunoassay shows that agrin binding to postsynaptic membranes is saturable and calcium-dependent. Half-maximal binding is observed at agrin concentrations < or = 10(-10) M. Identification of the bound agrin polypeptides shows that at least one membrane binding domain of agrin is located in a 70-kDa proteolytic fragment. Immunofluorescent visualization and radioimmunoassay of agrin binding demonstrates that the agrin receptor is selectively concentrated in postsynaptic membranes, with little binding detected on nonsynaptic or liver membranes. Agrin binding is greatly reduced if the membranes are pretreated with trypsin, but is unaffected by phosphatidylinositol-specific phospholipase C. Membranes stripped of peripheral proteins by alkaline treatment retain full ligand binding capacity. alpha-Bungarotoxin affinity columns bind AChRs but not agrin receptors. The ratio of agrin receptors to AChRs in postsynaptic membranes is approximately 1:200. We conclude that the agrin receptor is an integral membrane glycoprotein that is selectively concentrated in postsynaptic membranes, but that is not tightly complexed with the AChR. The results also indicate that the biological activity of agrin is mediated through intracellular signal transduction events triggered by ligand binding to the agrin receptor.
...
PMID:The agrin receptor. Localization in the postsynaptic membrane, interaction with agrin, and relationship to the acetylcholine receptor. 822 74

Endoglin is a homodimeric membrane glycoprotein primarily associated with human vascular endothelium. It is also found on bone marrow proerythroblasts, activated monocytes and on lymphoblasts in childhood leukemia. Endoglin has recently been described as a component of the transforming growth factor-beta (TGF-beta) receptor system as it can bind TGF-beta 1 with high affinity. We now report on the localization of the human endoglin gene (END) to human chromosome 9, by Southern blot analysis of BglII fragments of DNA from human-hamster somatic cell hybrids. This chromosomal localization was confirmed by fluorescent in situ hybridization coupled with Distamicin A (DA)/4',6-diamidino-2-phenylindole (DAPI) banding on human chromosomes. The regional localization was assigned to 9q34-->qter by GTG-banding (G-banding by trypsin using Giemsa stain), indicating a telomeric position with respect to the Philadelphia breakpoint.
...
PMID:Assignment of the human endoglin gene (END) to 9q34-->qter. 840 38

The T-cell activation antigen CD26, is a type II membrane glycoprotein with intrinsic dipeptidyl-peptidase IV (DPP IV) activity, characterized by its capacity to cleave off N-terminal dipeptides containing proline as the penultimate residue. Independent of its catalytic activity, CD26 has also been characterized as adenosine deaminase binding protein. By using CD26 negative human C8166 cells, here we describe the existence of another cell-surface protein which manifests CD26-like DPP IV activity. For convenience, this protein will be referred to as DPP IV-beta. Consistent with the cell-surface expression of DPP IV-beta, intact C8166 cells manifested a high level of DPP IV, whereas, they manifested poor activity against substrates of DPP II known to have an intracellular localization. A partially purified preparation of CD26 from human MOLT4 cells, and the DPP IV-beta expressed on intact cells were found to possess similar catalytic activity and pH optimum. In addition, cell-surface CD26 and DPP IV-beta on intact MOLT4 and C8166 cells, respectively, resisted digestion by proteolytic enzymes such as trypsin and proteinase K. However, adenosine deaminase activity was not detectable on the surface of C8166 cells in contrast to CD26 positive MOLT4 cells. In accord with this, 125I-labeled adenosine deaminase which binds CD26 was found not to bind DPP IV-beta. Gel-filtration experiments using 0.5% Triton X-100 extracts from C8166 and MOLT4 cells, revealed that the apparent molecular mass of DPP IV-beta is 82 kDa, whereas that of CD26 is 110 kDa as expected. Taken together, our results suggest that DPP IV-beta is a CD26-like protein which could be characterized by distinct properties.
...
PMID:Dipeptidyl-peptidase IV-beta, a novel form of cell-surface-expressed protein with dipeptidyl-peptidase IV activity. 870 27

Mechanisms of ligand binding and activation of G protein-coupled receptors are particularly important, due to their ubiquitous expression and potential as drug targets. Molecular interactions between ligands and these receptors are best defined for small molecule ligands that bind within the transmembrane helices. Extracellular domains seem to be more important for peptide ligands, based largely on effects of receptor mutagenesis, where interference with binding or activity can reflect allosteric as well as direct effects. We now take the more direct approach of photoaffinity labeling the active site of the cholecystokinin (CCK) receptor, using a photolabile analogue of CCK having a blocked amino terminus. This probe, 125I-desaminotyrosyl-Gly-[Nle28,31, pNO2-Phe33]CCK-(26-33), binds specifically, saturably, and with high affinity (Ki = 3.3 nM) and has full agonist activity. This makes likely its being sited in a natural position within the receptor. As substrate, we used CHO-CCK receptor cells overexpressing functional recombinant rat type A CCK receptor. Covalent labeling of the appropriate Mr = 85,000-95,000 plasma membrane glycoprotein with core of Mr = 42,000 was established by SDS-polyacrylamide gel electrophoresis and autoradiography. A single domain adjacent to transmembrane 1 was labeled, as established by cyanogen bromide cleavage and separation by gel and/or high pressure liquid chromatography. The site of interaction was further defined by additional proteolysis with trypsin, with purification of the labeled fragment, followed by manual Edman degradation and radiochemical sequencing. This demonstrated that Trp39 was specifically labeled and likely resides proximate to the carboxyl-terminal pNO2-Phe33 residue of the probe. A model of this ligand-bound receptor has been constructed and will be used to plan future experiments to refine our understanding of this interaction.
...
PMID:Direct identification of a distinct site of interaction between the carboxyl-terminal residue of cholecystokinin and the type A cholecystokinin receptor using photoaffinity labeling. 930 98

Human breast carcinoma MCF-7/AdrVp cells display a novel multidrug resistance phenotype that is characterized by the overexpression of a 95-kDa membrane glycoprotein (p95) and by marked reduction in intracellular anthracycline accumulation, without overexpression of P-glycoprotein or the multidrug resistance protein MRP. p95 is also highly expressed in multidrug-resistant NCI-H1688 cells derived from a human small cell lung carcinoma. Deglycoslyated p95 from NCI-H1688 cells was isolated by two-dimensional gel electrophoresis and then digested with trypsin. The tryptic peptides were analyzed by mass spectrometry and microsequencing. These analyses identified p95 to be identical to NCA-90, the nonspecific cross-reacting antigen related to the carcinoembryonic antigen (CEA). Further confirmation that p95 is indeed NCA-90 was obtained by Northern and Western blot studies using probes or antibodies specific for p95, NCA-90, or CEA family members. Western blot studies also revealed that CEA itself is overexpressed in MCF-7/AdrVp cells compared to parental MCF-7/W cells. The enforced expression of NCA-90 protein in HeLa cells stably transfected with NCA-90 cDNA did not result in increased resistance of the transfected cells to daunorubicin or a decrease in daunorubicin accumulation in the transfected cells compared to cells transfected only with the expression vector. However, a recent report by H. Kawaharata et al. (Int. J. Cancer, 72: 377-382, 1997) of diminished accumulation, retention, and cytotoxicity of doxorubicin in EJNIH3T3 cells in which enforced expression of CEA was accomplished leaves open the possibility that the overexpression of CEA, possibly in combination with that of NCA-90, could account at least in part for the drug resistant phenotype displayed by MCF-7/AdrVp cells.
...
PMID:The 95-kilodalton membrane glycoprotein overexpressed in novel multidrug-resistant breast cancer cells is NCA, the nonspecific cross-reacting antigen of carcinoembryonic antigen. 940 50

Newly developed photosensitive analogues of AngIV were used to characterize the AT4 receptor of bovine aortic endothelial cells. The photoactivatable AngIV analogues [N3-Phe6]AngIV and [Bpa6]AngIV displayed high affinities for AT4 receptor, with IC50's of 3.7 +/- 0.3 and 19.1 +/- 3.5 nM, respectively. The radioiodinated ligands showed a good efficiency of photoaffinity labeling demonstrated by high proportions (60-75%) of acid-resistant binding. Covalently labeled receptor was solubilized under reducing or nonreducing conditions and subjected to SDS-PAGE. Under nonreducing conditions, autoradiographies revealed a major band of Mr 186 +/- 2 kDa and a minor band of Mr 241 +/- 6 kDa. The labeling of these bands was completely abolished in the presence of 10 microM AngIV. Under reducing conditions, only the low Mr 186 kDa band was revealed. After endoglycosidase digestion with an enzyme that cleaves N-linked saccharides, the Mr of the denatured AT4 receptor was decreased by 31% to a value of 129 +/- 10 kDa. Kinetic studies revealed a stepwise process of AT4 receptor deglycosylation by endoglycosidase F, suggesting at least two different sites of N-linked saccharides. Mild trypsin treatment of photolabeled endothelial cell membranes released a large fragment of Mr 177 +/- 3 kDa which accounts for about 95% of the whole receptor molecular mass. These results demonstrate that [N3-Phe6]AngIV and [Bpa6]AngIV are very efficient tools for selective photoaffinity labeling of AT4 receptor. We have shown that AT4 receptor is a 186 kDa integral membrane glycoprotein with a very large extracellular domain. These properties are consistent with those of a growth factor or cytokine receptor.
...
PMID:Characterization of AT4 receptor from bovine aortic endothelium with photosensitive analogues of angiotensin IV. 952 51

Bovine parvovirus (BPV), an autonomous parvovirus, haemagglutinates human type O erythrocytes and infects certain bovine cells in culture. Little is known about the receptor to which it attaches, either on nucleated host cells or on erythrocytes. Haemagglutination assays and radiolabelled virus-binding tests measuring the effects of trypsin, chymotrypsin, neuraminidase, phospholipase C and sodium periodate on attachment of BPV to receptors indicated that BPV interacted with N-acetylneuraminic acid-containing (sialyl) glycoproteins. SDS-polyacrylamide gel separation of erythrocyte ghost proteins and virus overlay protein-binding revealed BPV binding to glycophorin A. Confirmation testing showed BPV binding to purified glycophorin A on dot blots and on gels containing membrane glycophorin A and purified glycophorin A. Further, in competition assays, purified glycophorin A completely inhibited the BPV haemagglutination reaction. The results of this study indicate that BPV binds to sialated membrane glycoproteins, one of which is the major erythrocyte membrane glycoprotein, glycophorin A.
...
PMID:Binding of bovine parvovirus to erythrocyte membrane sialylglycoproteins. 974 25

The cell surface retention sequence (CRS) binding protein-1 (CRSBP-1) is a newly identified membrane glycoprotein which is hypothesized to be responsible for cell surface retention of the oncogene v-sis and c-sis gene products and other secretory proteins containing CRSs. In simian sarcoma virus-transformed NIH 3T3 cells (SSV-NIH 3T3 cells), a fraction of CRSBP-1 was demonstrated at the cell surface and underwent internalization/recycling as revealed by cell surface 125I labeling and its resistance/sensitivity to trypsin digestion. However, the majority of CRSBP-1 was localized in intracellular compartments as evidenced by the resistance of most of the 35S-metabolically labeled CRSBP-1 to trypsin digestion, and by indirect immunofluorescent staining. CRSBP-1 appeared to form complexes with proteolytically processed forms (generated at and/or after the trans-Golgi network) of the v-sis gene product and with a approximately 140-kDa proteolytically cleaved form of the platelet-derived growth factor (PDGF) beta-type receptor, as demonstrated by metabolic labeling and co-immunoprecipitation. CRSBP-1, like the v-sis gene product and PDGF beta-type receptor, underwent rapid turnover which was blocked in the presence of 100 microM suramin. In normal and other transformed NIH 3T3 cells, CRSBP-1 was relatively stable and did not undergo rapid turnover and internalization/recycling at the cell surface. These results suggest that in SSV-NIH 3T3 cells, CRSBP-1 interacts with and forms ternary and binary complexes with the newly synthesized v-sis gene product and PDGF beta-type receptor at the trans-Golgi network and that the stable binary (CRSBP-1.v-sis gene product) complex is transported to the cell surface where it presents the v-sis gene product to unoccupied PDGF beta-type receptors during internalization/recycling.
...
PMID:Cell surface retention sequence binding protein-1 interacts with the v-sis gene product and platelet-derived growth factor beta-type receptor in simian sarcoma virus-transformed cells. 1018 53

Microtubule-associated protein (MAP) 1B is a high-molecular-weight cytoskeletal protein that is abundant in developing neuronal processes and appears to be necessary for axonal growth. Various biochemical and immunocytochemical results are reported, indicating that a significant fraction of MAP1B is expressed as an integral membrane glycoprotein in vesicles and the plasma membrane of neurons. MAP1B is present in microsomal fractions isolated from developing rat brain and fractionates across a sucrose gradient in a manner similar to synaptophysin, a well-known vesicular and plasma membrane protein. MAP1B is also in axolemma-enriched fractions (AEFs) isolated from myelinated axons of rat brain. MAP1B in AEFs and membrane fractions from cultured dorsal root ganglion neurons (DRGNs) remains membrane-associated following high-salt washes and contains sialic acid. Furthermore, MAP1B in intact DRGNs is readily degraded by extracellular trypsin and is labeled by the cell surface probe sulfosuccinimidobiotin. Immunocytochemical examination of DRGNs shows that MAP1B is concentrated in vesicle-rich varicosities along the length of axons. Myelinated peripheral nerves immunostained for MAP1B show an enrichment at the axonal plasma membrane. These observations demonstrate that some of the MAP1B in developing neurons is an integral plasma membrane glycoprotein.
...
PMID:Evidence for expression of some microtubule-associated protein 1B in neurons as a plasma membrane glycoprotein. 1089 30


<< Previous 1 2 3 4 5 6 7 Next >>

---