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41.
Transforming growth factor-alpha in the mammalian brain. Immunohistochemical detection in neurons and characterization of its mRNA 总被引:5,自引:0,他引:5
J E Kudlow A W Leung M S Kobrin A J Paterson S L Asa 《The Journal of biological chemistry》1989,264(7):3880-3883
In this communication, we demonstrate that adult mammalian brain neurons express transforming growth factor-alpha (TGF-alpha). We used the anti-TGF-alpha monoclonal antibody, MF9, to immunohistochemically localize TGF-alpha in human and rat brain. We found specific immunoreactivity in neurons throughout the brain which was not a result of cross-reactivity of MF9 with the neuropeptide, synenkephalin. Northern blot analysis of bovine and rat brain RNA using human and rat TGF-alpha cDNA probes, respectively, revealed a single 4.8-kilobase pair mRNA with approximately equal abundance in the bovine brainstem, cerebellum, hypothalamus, and cerebral cortex. Fetal rat brain had about 2-fold more TGF-alpha mRNA than did adult rat. The brain TGF-alpha cDNA was cloned from a human neonatal brainstem library. Four identical clones were isolated after screening 10(6) recombinant lambda gt11 phage. The sequence of the 894-base pair cDNA was virtually identical with the cDNA isolated from a human renal cell carcinoma. A single alanine codon was deleted in the brain cDNA at an exon-exon junction. The alanine deletion is within the amino-terminal region of the TGF-alpha precursor that is thought to be removed by proteolytic processing of the precursor to the mature growth factor. These studies indicate that the normal mammalian brain neurons express TGF-alpha. 相似文献
42.
Subcellular distribution of the 1,4-dihydropyridine receptor in rabbit skeletal muscle in situ: an immunofluorescence and immunocolloidal gold- labeling study 总被引:15,自引:9,他引:6
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A O Jorgensen A C Shen W Arnold A T Leung K P Campbell 《The Journal of cell biology》1989,109(1):135-147
The subcellular distribution of the 1,4-dihydropyridine receptor was determined in rabbit skeletal muscle in situ by immunofluorescence and immunoelectron microscopy. Longitudinal and transverse cryosections (5-8 microns) of rabbit gracilis muscle were labeled with monoclonal antibodies specific against either the alpha 1-subunit (170,000-D polypeptide) or the beta-subunit (52,000-D polypeptide) of the 1,4-dihydropyridine receptor by immunofluorescence labeling. In longitudinal sections, specific labeling was present only near the interface between the A- and I-band regions of the sarcomeres. In transverse sections, specific labeling showed a hexagonal staining pattern within each myofiber however, the relative staining intensity of the type II (fast) fibers was judged to be three- to fourfold higher than that of the type I (slow) fibers. Specific immunofluorescence labeling of the sarcolemma was not observed in either longitudinal or transverse sections. These results are consistent with the idea that the alpha 1-subunit and the beta-subunit of the purified 1,4-dihydropyridine receptor are densely distributed in the transverse tubular membrane. Immunoelectron microscopical localization with a monoclonal antibody to the alpha 1-subunit of the 1,4-dihydropyridine receptor showed that the 1,4-dihydropyridine receptor is densely distributed in the transverse tubular membrane. Approximately half of these were distributed in close proximity to the junctional region between the transverse tubules and the terminal cisternae. Specific labeling was also present in discrete foci in the subsarcolemmal region of the myofibers. The size and the nonrandom distribution of these foci in the subsarcolemmal region support the possibility that they correspond to invaginations from the sarcolemma called caveolae. In conclusion, our results demonstrate that the 1,4-dihydropyridine receptor in skeletal muscle is localized to the transverse tubular membrane and discrete foci in the subsarcolemmal region, possibly caveolae but absent from the lateral portion of the sarcolemma. 相似文献
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Summary The simultaneous presence of 6-benzyladenine (BA) and sucrose in a Murashige and Skoog medium (SIM) during the initial stages of shoot initiation have been found to be obligatory for high-frequency shoot formation in the Capsicum annuum L. var. Sweet Banana upper hypocotyl explants. The explants are determined for shoot formation following a minimum of 8 days of culture on SIM. Deprivation of exogenous sucrose from day 6 to day 20 of culture had no effect on the shoot forming response of the explants. BA and sucrose appear to act independently on different aspects of the competence of explants to respond to SIM during shoot initiation.Abbreviations BA
N6-benzyladenine
- MS
Murashige and Skoog medium
- SIM
shoot induction medium
- HFM
hormone free medium
- SUC
sucrose minus medium 相似文献
45.
The p160 RhoA-binding kinase ROK alpha is a member of a kinase family and is involved in the reorganization of the cytoskeleton. 总被引:29,自引:5,他引:24
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The GTPase RhoA has been implicated in various cellular activities, including the formation of stress fibers, motility, and cytokinesis. We recently reported on a p150 serine/threonine kinase (termed ROK alpha) binding RhoA only in its active GTP-bound state and on its cDNA; introduction of RhoA into HeLa cells resulted in translocation of the cytoplasmic kinase to plasma membranes, consistent with ROK alpha being a target for RhoA (T. Leung, E. Manser, L. Tan, and L. Lim, J. Biol. Chem. 256:29051-29054, 1995). Reanalysis of the cDNA revealed that ROK alpha contains an additional N-terminal region. We also isolated another cDNA which encoded a protein (ROK beta) with 90% identity to ROK alpha in the kinase domain. Both ROK alpha and ROK beta, which had a molecular mass of 160 kDa, contained a highly conserved cysteine/histidine-rich domain located within a putative pleckstrin homology domain. The kinases bound RhoA, RhoB, and RhoC but not Rac1 and Cdc42. The Rho-binding domain comprises about 30 amino acids. Mutations within this domain caused partial or complete loss of Rho binding. The morphological effects of ROK alpha were investigated by microinjecting HeLa cells with DNA constructs encoding various forms of ROK alpha. Full-length ROK alpha promoted formation of stress fibers and focal adhesion complexes, consistent with its being an effector of RhoA. ROK alpha truncated at the C terminus promoted this formation and also extensive condensation of actin microfilaments and nuclear disruption. The proteins exhibited protein kinase activity which was required for stress fiber formation; the kinase-dead ROK alpha K112A and N-terminally truncated mutants showed no such promotion. The latter mutant instead induced disassembly of stress fibers and focal adhesion complexes, accompanied by cell spreading. These effects were mediated by the C-terminal region containing Rho-binding, cysteine/histidine-rich, and pleckstrin homology domains. Thus, the multidomained ROK alpha appears to be involved in reorganization of the cytoskeleton, with the N and C termini acting as positive and negative regulators, respectively, of the kinase domain whose activity is crucial for formation of stress fibers and focal adhesion complexes. 相似文献
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48.
Mark D. Wittman John F. Kadow Kahnie Pham Leung Kinwa Harold A. Mastalerz Dolatrai M. Vyas William C. Rose Wyle Solomon Nada Zein 《Bioorganic & medicinal chemistry letters》1994,4(24):2925-2928
The thiol activation and aromatization of bicyclo[7.1.0]enediynes was found to be dependent of the nature of the propargyl substituent. These effects are correlated to antitumor activity. 相似文献
49.
Differential regulation of vascular cell adhesion molecule 1 gene expression by specific NF-kappa B subunits in endothelial and epithelial cells. 总被引:21,自引:5,他引:16
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H B Shu A B Agranoff E G Nabel K Leung C S Duckett A S Neish T Collins G J Nabel 《Molecular and cellular biology》1993,13(10):6283-6289
50.
An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. 相似文献