Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A stoichiometric complex formed between human alpha-thrombin and D-Phe-Pro-Arg chloromethylketone was crystallized in an orthorhombic crystal form. Orientation and position of a starting model derived from homologous modelling were determined by Patterson search methods. The thrombin model was completed in a cyclic modelling-crystallographic refinement procedure to a final R-value of 0.171 for X-ray data to 1.92 A. The structure is in full agreement with published cDNA sequence data. The A-chain, ordered only in its central part, is positioned along the molecular surface opposite to the active site. The B-chain exhibits the characteristic polypeptide fold of trypsin-like proteinases. Several extended insertions form, however, large protuberances; most important for interaction with macromolecular substrates is the characteristic thrombin loop around Tyr60A-Pro60B-Pro60C-Trp60D (chymotrypsinogen numbering) and the enlarged loop around the unique Trp148. The former considerably restricts the active site cleft and seems likely to be responsible for poor binding of most natural proteinase inhibitors to thrombin. The exceptional specificity of D-Phe-Pro-Arg chloromethylketone can be explained by a hydrophobic cage formed by Ile174, Trp215, Leu99, His57, Tyr60A and Trp60D. The narrow active site cleft, with a more polar base and hydrophobic rims, extends towards the arginine-rich surface of loop Lys70-Glu80 that probably represents part of the anionic binding region for hirudin and fibrinogen.
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PMID:The refined 1.9 A crystal structure of human alpha-thrombin: interaction with D-Phe-Pro-Arg chloromethylketone and significance of the Tyr-Pro-Pro-Trp insertion segment. 258 8

Mucin-like cancer-associated antigen (MCA), a new tumor marker using the mouse monoclonal antibody b-12 is thought to be of value in the management of patients with breast cancer. In this study sera from 191 female patients with breast cancer (112 with progressive disease [PD] and 79 with no evidence of disease [NED]) were analyzed for MCA levels and compared with those of cancer antigen 15-3 (CA 15-3) in single determination and in combination with carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA). A cut-off level of 14 U/ml for MCA seems to be more appropriate than the recommended 11 U/ml to distinguish between PD and NED in patients with breast cancer. Although there was a fairly good correlation of MCA to CA 15-3, MCA was inferior in sensitivity and specificity to CA 15-3. Patients with osseous metastases and those with more than one metastatic site showed higher MCA levels than patients with visceral or soft tissue metastases, a fact which was comparable to CA 15-3. Combining MCA and CA 15-3 resulted in a gain in specificity but marked loss of sensitivity. The combination of MCA and CEA results also in a loss of sensitivity whereas the combination of CA 15-3 and CEA showed an increased specificity and only a negligible loss of sensitivity. The combination of MCA with TPA is of little value in the follow-up of breast cancer, as is the combination of CA 15-3 with TPA. The combination of CA 15-3 with CEA can be still recommended for follow-up for early detection of metastases in breast cancer.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mucin-like cancer-associated antigen (MCA) compared with CA 15-3 in advanced breast cancer. 279 51

Mucin glycoproteins are major secretory products of the colon and contain O-linked oligosaccharides synthesized on a polypeptide backbone. The initial step in the synthesis of O-linked oligosaccharides is the addition of N-acetylgalactosamine to serine or threonine residues forming the Tn antigen. This substance can then receive additional carbohydrate residues such as sialic acid to form sialosyl-Tn antigen, or galactose to form T antigen. In the colon, the T antigen is an oncodevelopmental cancer-associated antigen but little is known about Tn and sialosyl-Tn expression. The present comparative immunohistochemical study was performed to analyze the expression of these antigens in fetal, normal adult, and malignant colorectal tissues with an aim toward elucidating whether Tn and sialosyl-Tn are also oncodevelopmental colon cancer-associated antigens and to gain insight into the earliest steps of mucin glycosylation in colonocytes. We used three reagents to detect Tn antigen (two monoclonal antibodies ETn1.01 and CU-1, and one lectin Vicia villosa), two reagents to detect sialosyl-Tn (monoclonal antibodies TKH2 and B72.3) and one to detect T antigen (monoclonal antibody AH9-16). Except for occasional reactivity with VVA and CU-1, cells of normal colonic mucosa did not express Tn, sialosyl-Tn, or T antigens. However, in the transitional mucosa immediately adjacent to cancer, all three antigens were expressed (ranging from 35 to 67% of cases depending upon the reagent). In colon cancers, the percentage of cases expressing each antigen were as follows: Tn 72-81%, sialosyl-Tn 93-96%, and T 71%. Unlike T antigen, which was preferentially expressed by moderately well- and well-differentiated adenocarcinomas, both Tn and sialosyl-Tn antigens were expressed by most histological subsets of colon cancers, including poorly differentiated adenocarcinomas and mucinous (colloid and signet ring cell type) carcinomas. The majority of cancers expressed both Tn and sialosyl-Tn, usually in association with T antigen. Only one cancer lacked all three antigens. Fetal colonic mucosal cells expressed all three antigens, particularly in goblet cell mucin. These results indicate that like T antigen, Tn and sialosyl-Tn are oncodevelopmental cancer-associated antigens in the colon. Moreover, Tn and sialosyl-Tn antigens appear to be useful markers of poorly differentiated adenocarcinomas and mucinous carcinomas: two histological subsets that often fail to express other cancer-associated antigens and that are often associated with a poor clinical outcome.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Expression of Tn, sialosyl-Tn, and T antigens in human colon cancer. 290 46

Mucin has been purified from nude mouse xenografts of SW1990 human pancreatic cancer cells. The mucin was eluted at the void volume of Sepharose CL-4B and was of density greater than 1.3 in CsCl gradients. The isolated mucin had a high content of threonine, serine, and proline, with 31% of the amino acid residues O-glycosylated. The average oligosaccharide composition was NeuAc1.8Fuc0.7Gal2.0GlcNAc1.7GalNAc1.4. Polyclonal rabbit antibodies prepared against the purified mucin recognized primarily mucin polypeptide, and there was extensive immunological cross-reaction between SW1990 pancreatic cancer mucin and LS174T colon cancer mucin. However, using carbohydrate-specific monoclonal antibodies, the two mucins were found to differ. SW1990 mucin had more Lewis, sialyl Lewis, and sialyl Lewis activity, while the colon cancer mucin had more sialyl T antigen. Since pancreatic mucins, whether from normal pancreas or pancreatic cancer, have not previously been well characterized, the availability of SW1990 pancreatic cancer mucin may be useful as a model for studying the expressing of organ-specific or cancer-associated antigens.
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PMID:Pancreatic cancer mucin from xenografts of SW1990 cells: isolation, characterization, and comparison to colon cancer mucin. 322 46

Restoration of the circadian rhythmicity in wheel-running activity was shown in rats with bilateral suprachiasmatic nuclei (SCN) lesions, after transplantation of the neonatal SCN into the wall of the third ventricle. Free-running circadian rhythms of the wheel-running activity were recorded in young adult rats at least for a month under constant dark condition. Then, bilateral SCNs were completely lesioned electrolytically under deep pentobarbital anaesthesia. After further recording for more than two months without obvious circadian rhythmicity in wheel-running activity, the animals were subjected to transplantation of the SCN. SCNs taken from day 1 neonatal rats were transplanted by injecting the grafts into the third ventricle of the host rat under pentobarbital anaesthesia. After recovery from the procedure, the rat was returned to a cage with a running wheel. Food and water were available at all times. Successful transplantation led to restoration of the circadian rhythmicity starting from two weeks and up to three months after the transplantation. To identify the SCN in the transplanted graft, we used an immunohistochemical staining method for the VIP (vasoactive intestinal polypeptide) and vasopressin. The VIP was located particularly in the ventral area of the SCN, whereas vasopressin was in the dorsal area. In most cases, where circadian rhythmicity was successfully restored, the graft was attached to the caudal wall of the third ventricle.
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PMID:Transplantation of the suprachiasmatic nucleus in the rat. 348 39

The nucleocapsid of the enveloped double-stranded RNA bacteriophage phi 6 was isolated by extraction with the nonionic detergent Triton X-114 and subjected to disruption analysis with chelating and protein-denaturing agents. The subnucleocapsid particles were separated in rate-zonal sucrose gradients, and their ultrastructure and protein composition were analyzed. The role of divalent cations in the nucleocapsid structure was studied by using a precipitation assay of the isolated nucleocapsid proteins. The phi 6 nucleocapsid had a cagelike skeleton consisting of a single polypeptide species (P1). Two other proteins (P2 and P4) were associated with the P1 cage. These three early proteins were previously known to be involved in the RNA synthesis machinery of the virus. The stability of the nucleocapsid surface lattice consisting of protein P8 was dependent on Ca2+ ions.
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PMID:The nucleocapsid of the lipid-containing double-stranded RNA bacteriophage phi 6 contains a protein skeleton consisting of a single polypeptide species. 359 79

ATP hydrolysis was used to power the enzymatic release of clathrin from coated vesicles. The 70,000-mol-wt protein, purified on the basis of its ATP-dependent ability to disassemble clathrin cages, was found to possess a clathrin-dependent ATPase activity. Hydrolysis was specific for ATP; neither dATP nor other ribonucleotide triphosphates would either substitute for ATP or inhibit the hydrolysis of ATP in the presence of clathrin cages. The ATPase activity is elicited by clathrin in the form of assembled cages, but not by clathrin trimers, the product of cage disassembly. The 70,000-mol-wt polypeptide, but not clathrin, was labeled by ATP in photochemical cross-linking, indicating that the hydrolytic site for ATP resides on the uncoating protein. Conditions of low pH or high magnesium concentration uncouple ATP hydrolysis from clathrin release, as ATP is hydrolyzed although essentially no clathrin is released. This suggests that the recognition event triggering clathrin-dependent ATP hydrolysis occurs in the absence of clathrin release, and presumably precedes such release.
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PMID:Dissociation of clathrin coats coupled to the hydrolysis of ATP: role of an uncoating ATPase. 614 31

Bullock brain coated vesicles contain a family of at least six 100-kd polypeptides which have the property of promoting clathrin assembly. These proteins have been purified from Triton X-100-extracted coated vesicles by a combination of gel filtration and chromatography on hydroxylapatite and DE-52 cellulose. Three major 100-kd species occur as complexes with a stoichiometric amount of a 50-kd polypeptide. On cross-linking these complexes, the chief products appear to contain two polypeptides of 100 kd and two of 50 kd. These 100-kd/50-kd complexes will polymerise with low concentrations of clathrin to give a relatively homogeneous population of coats predominantly of the 'barrel' size. In contrast, three other polypeptides of 100 kd lack the 50-kd protein but polymerise with clathrin under the same conditions to yield coats of a wide range of sizes including 'barrels', truncated icosahedra and particles of greater than 100 nm diameter. When clathrin cages are reassembled with a saturating amount of 100-kd/50-kd complexes and studied by electron microscopy, the additional proteins appear to follow the underlying geometry of the clathrin polyhedra, partially filling in the polygonal faces of the cage structures. Saturation appears to require approximately 3 molecules of 100-kd polypeptide per clathrin trimer.
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PMID:Purification and properties of 100-kd proteins from coated vesicles and their reconstitution with clathrin. 614 17

Mitotic cells have been detergent extracted under conditions that support microtubule assembly. When HeLa cells are lysed in the presence of brain tubulin, mitotic-arrested cells nucleate large asters and true metaphase cells yield spindles that remain enclosed within a roughly spherical cage of filamentous material. Detergent-extracted mitotic Chinese hamster ovary (CHO) cells show a similar, insoluble cage but the mitotic apparatus is only occasionally stabilized. In later stages of mitosis, HeLa cages are observed in elongated and furrowed configurations. In the terminal stages of cell division, two daughter filamentous networks are connected by the intercellular bridge. When observed in the electron microscope the cages include fibers 7-11 nm in diameter. The polypeptide composition of cages isolated from mitotic HeLa cells is complex, but the major polypeptides are a group with mol wt ranging from 43,000-60,000 daltons and a high molecular weight polypeptide. CHO cells contain a subset of these proteins which includes a major 58,000-dalton and a high molecular weight polypeptide. Two different antisera directed against the vimentin-containing intermediate filaments bind to polypeptides in the electrophoretic profiles of isolated HeLa and CHO cages and stain the cages, as visualized by indirect immunofluorescence. These results suggest that the HeLa and CHO cages include intermediate filaments of the vimentin type. The polypeptide composition of HeLa cages suggests that they also contain tonofilaments. The cages apparently form as the cells enter mitosis. We propose that these filamentous cages maintain the structural continuity of the cytoplasm while the cell is in mitosis.
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PMID:Isolation and partial characterization of a cage of filaments that surrounds the mammalian mitotic spindle. 719 25

The basal body cage is a fibrillar chamber which surrounds each basal body in the ciliate cytoskeleton. The function of this chamber is unknown. In Tetrahymena, the cage contains actin filaments which connect the cage to triplet microtubules. In this study, we have examined the cage for the presence of myosin. Skeletal muscle myosin-II heavy and light chains were used to affinity-purify anti-MHC and anti-MLC antibodies, respectively, from an antiserum raised against Tetrahymena oral apparatus proteins. On western immunoblots of ATP-solubilized Tetrahymena proteins, the anti-MHC antibody detected a putative myosin heavy (180 kDa) chain, and the anti-MLC antibody detected a putative myosin light (18 kDa) chain. The anti-MHC antibody specifically labeled the AI zone of sarcomeres. In cosedimentation assays with an ATP-solubilized protein fraction, the 180 kDa polypeptide associated with skeletal muscle actin filaments in an ATP-dependent manner. The sedimented actin filaments appeared to be organized into bundles. Immunodepletion of the 180 kDa rendered the ATP-solubilized protein fraction ineffective in bundling actin filaments in a cosedimentation assay. ATP-solubilized Tetrahymena proteins, which included the 180 kDa polypeptide, exhibited F-actin-stimulated, Mg2+ ATPase activity and K+, EDTA ATPase activity which are characteristic of myosin ATPases. Immunodepletion of the 180 kDa polypeptide reduced the F-actin, Mg2+ ATPase activity of the ATP-solubilized protein fraction by more than 80%. Based on these various observations, we conclude that the 180 kDa polypeptide is a putative myosin heavy chain, probably a myosin-II and that the 18 kDa polypeptide is probably a myosin-II light chain. We have used the affinity-purified, anti-myosin antibodies with immunofluorescence microscopy and immunogold electron microscopy to map the location of the putative myosin heavy and light chains in Tetrahymena. Immunofluorescence microscopy showed that the anti-myosin antibodies localized to Tetrahymena somatic and oral region basal bodies. At the ultrastructural level, the anti-myosin antibodies localized to filaments in the basal body-cage complex. The labeling patterns with both anti-myosin antibodies were identical to the labeling pattern observed with an anti-actin antibody reported in a previous study. The co-localization of myosin and actin argue for a motility system within the basal body-cage complex.
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PMID:Putative myosin heavy and light chains in Tetrahymena: co-localization to the basal body-cage complex and association of the heavy chain with skeletal muscle actin filaments in vitro. 762 16


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