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

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ovarian and Leydig cell LH/hCG receptors purified to homogeneity were identified as a single protein of Mr 80,000 and 90,000 respectively. The homogeneity of this protein was confirmed by microsequencing of the first 18 amino acids of the ovarian receptor. The unblocked N-terminal peptide consisted of NH2-R-E-L-S-G-S-R-X-P-E-P-X-D-X-A-P-D-G. These receptors are N-linked sialoglycoproteins which accounts for the size difference between testicular and ovarian receptors and may participate in the interaction with gonadotropin. Crosslinking of pure receptor with hCG with 125I label in either subunit indicated significant interaction of alpha-hCG with the receptor, while beta-hCG seems involved mostly through association and conformational influence on the alpha-subunit. Comparison of Mr derived from SDS with those from FPLC suggested that the native LH receptor are dimers of identical subunits. Autoradiographs of blotted receptors demonstrated that both monomeric and dimeric forms can bind hCG. Receptors from both tissues can be phosphorylated by the catalytic subunit of cAMP-dependent protein kinase and phosphopeptide maps were identical. Receptor occupancy by agonist leads to a conformational change which facilitates its phosphorylation during initial binding and reduces the rate of phosphorylation after more prolonged exposure to gonadotropin. Aggregation or dimerization of the hCG/LH receptors could promote clustering and or crosslinking of receptors in the membrane favouring the initial transduction steps in the action of these hormones.
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PMID:Characterization and structure of ovarian and testicular LH/hCG receptors. 260 25

The mos oncogene of Moloney murine sarcoma virus encodes a protein of approximately 37,000 daltons (designated p37mos). We have detected a serine protein kinase activity which is closely associated with p37mos in immune complexes obtained with antibodies [anti-mos(37-55) serum] that were generated with a peptide containing amino acids 37 through 55 of the v-mos protein (S. A. Maxwell and R. B. Arlinghaus, Virology 143:321-333, 1985). Immune complexes that were derived with antibodies generated against peptides representing the C-terminal 8 or 12 amino acids of v-mos (anti-C2 and anti-C3 serum, respectively) exhibited very little kinase activity capable of phosphorylating p37mos. Treatment of anti-mos(37-55) complexes containing active v-mos kinase with anti-C3 or anti-C2 serum resulted in a dramatic reduction of the in vitro phosphorylation of p37mos. Antiserum blocked with the appropriate C-terminal peptide had no inhibitory effect on the phosphorylation of p37mos in anti-mos(37-55) complexes which indicated that the inhibition of v-mos kinase activity was a specific effect of these antibodies. The specific inhibition of the in vitro phosphorylation of p37mos by antibodies directed against the C terminus of the v-mos protein provides strong evidence that the v-mos gene encodes a serine protein kinase. In addition, the extreme C terminus of p37mos may be critical for an active v-mos kinase.
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PMID:Use of site-specific antipeptide antibodies to perturb the serine kinase catalytic activity of p37mos. 299 8

The literary and experimental data on the structure and properties of cardiac and skeletal muscle troponin are reviewed. The cation--binding sites of cardiac and skeletal muscle troponin C are distinguished by specificity; the sites localized in the C-terminal part of the protein molecule can bind both Ca2+ and Mg2+, whereas the sites localized at the N-end specifically bind Ca2+. The use of bifunctional reagents revealed a number of helical sites within the structure of cardiac troponin C (residues 84-92 and 150-158) and of skeletal muscle troponin C (residues 90-98 and 125-136). A comparison of experimental data with the results of an X-ray analysis testifies to the presence in the central part of the troponin C molecule of a long alpha-helical sequence responsible for troponin C interaction with the inhibiting peptide of troponin I. The efficiency of interaction of troponin components depends on Ca2+ concentration; the integrity of the overall troponin complex is mainly provided for by troponin C interaction with troponin I and by troponin I interaction with troponin T. The interaction between troponins T and C is relatively weak, especially in the case of cardiac troponin components. Both skeletal and cardiac muscles synthesize several troponin T isoforms differing in length and amino acid composition of N-terminal 40-60 member peptides. Troponin T isoforms can undergo phosphorylation by several protein kinases. The single site of troponin T which exists in a phosphorylated state in vivo (residue Ser-1) undergoes phosphorylation by specific protein kinase (troponin T kinase) related to casein kinases II. It was assumed that the phosphorylation of Ser-1 residue of troponin T as well as the synthesis of troponin T isoforms differing in the structure of the N-terminal peptide, provides for the regulation of interaction between two neighbouring tropomyosin molecules.
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PMID:[Troponin from the myocardium and skeletal muscles: structure and properties]. 354 61

7B2 is a 23-kDa protein encoded by a single gene that is expressed in a variety of neuroendocrine tissues. Although its physiological role has not yet been elucidated, its presence in secretory granules suggests a function in the secretory machinery of certain neuronal and endocrine cells in various species. The present study characterizes the expression of 7B2 in endocrine pancreatic cells. We demonstrate that: (i) 7B2 is highly expressed in human insulinomas; (ii) its ultrastructural localization, associated with secretory granules of A and B cells of the islets, suggests a participation of 7B2 in the secretion of insulin and glucagon; (iii) sequences located in the first intron of the 7B2 gene are required for its transcription in either insulinoma or glucagonoma cell lines; and (iv) in a B cell-like insulinoma cell line, the transcription of 7B2 is regulated by protein kinase A and protein kinase C activators, while in an A-like insulinoma cell line, 7B2 gene transcription seems to be constitutively activated.
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PMID:Expression, intracellular localization, and gene transcription regulation of the secretory protein 7B2 in endocrine pancreatic cell lines and human insulinomas. 751 67

The tolerance of bacteriophage lambda morphogenesis for C-terminal additions to the tail tube major protein subunit (the V gene product; gpV) has been investigated. A second modified copy of the lambda V gene, either within a novel phage vector itself or plasmid-borne, was expressed during phage growth. High-level substitution of wild-type gpV by modified gpV bearing a basic C-terminal peptide sequence (RRASV; a target site for cAMP-dependent protein kinase) was possible using multiple repeats of a serine-glycine (SGGG) linker sequence. Highly purified phage bearing copies of gpV-RRASV could be efficiently phosphorylated by the appropriate protein kinase, and the incorporated label was shown to migrate exclusively at the expected size in protein gels. A large tetrameric protein (beta-galactosidase) could be incorporated into active virions in at least one copy, again using a Ser-Gly linker. These studies suggest that with a suitable spacing linker and controlled levels of expression, it is likely that a wide range of protein or peptide substitutents can be fused with gpV at its C terminus and assembled as component subunits of the tail tube.
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PMID:Assembly of functional bacteriophage lambda virions incorporating C-terminal peptide or protein fusions with the major tail protein. 775 19

A caldesmon kinase activity was partially purified from an extract of chicken gizzard smooth muscle by sequential chromatography on columns of DEAE-Sephacel, MonoQ and Superose 12. This kinase was identified as casein kinase II by Western blotting using peptide-directed antibodies raised against the alpha, alpha' and beta subunits of human casein kinase II; the smooth muscle enzyme consisted of similar subunits of M(r) 43,000 (alpha), 39,000 (alpha'), and 27,000 (beta). Phosphorylation of caldesmon and casein by smooth muscle casein kinase II was optimal at approximately 0.1 M NaCl, did not require second messengers, and was inhibited by heparin. The kinase utilized either GTP or ATP as a substrate. Caldesmon was phosphorylated to approximately 1 mol Pi mol-1 caldesmon by smooth muscle casein kinase II with a Km for caldesmon of 4.9 microM. Two-dimensional thin-layer electrophoresis indicated phosphate incorporation into both serine and threonine. All the incorporated phosphate was recovered in the N-terminal peptide (residues 1-152) generated by cleavage at cysteine 153 with 2-nitro-5-thiocyanobenzoic acid. Purification of tryptic phosphopeptides and N-terminal sequencing revealed two principal sites of phosphorylation: serine 73 and threonine 83. The following four synthetic peptides corresponding to this domain of caldesmon were examined as substrates of casein kinase II: A = RRREVNAQNSVAEEE; B = AQNSVAEEE; C = RSTDDEAA; D = SVAEEETKRSTDDE. Interestingly, only peptides C and D were phosphorylated and both only at threonine. Phosphorylation of intact caldesmon did not affect the pattern of chymotryptic digestion suggesting that it does not induce a significant conformational change in the protein substrate. Phosphorylation also had no effect on the binding of caldesmon to actin or on the caldesmon-mediated inhibition of actomyosin MgATPase activity. However, phosphorylation completely abolished the interaction of caldesmon with immobilized smooth muscle myosin. These results are consistent with the localization of the myosin-binding domain near the N-terminus of caldesmon and of the actin-binding domain near the opposite end of the elongated molecule. Casein kinase II may therefore play a role in regulating caldesmon-myosin interaction and the ability of caldesmon to cross-link actin and myosin filaments in smooth muscle.
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PMID:Phosphorylation of caldesmon by smooth-muscle casein kinase II. 780 38

The soybean seed basic 7S globulin (Bg) is capable of binding bovine insulin and insulin-like growth factors, and has protein kinase activity which corresponds to about two thirds of the tyrosine kinase activity of the rat insulin receptor. A 4-kDa peptide named leginsulin, which can bind to Bg and compete with insulin for binding to Bg, was isolated from radicles of germinated soybean seeds. The leginsulin had a stimulatory effect on the phosphorylation activity of Bg, suggesting that it is involved in cellular signal transduction. The leginsulin was sequenced by automated Edman degradation and electrospray ionization mass spectrometry. It consisted of 37 amino acid residues with six half-cystines in three disulfide bridges. The mass spectrometric analysis revealed that a portion of the peptide is processed to delete the C-terminal glycine like a number of animal peptide hormones, but not C-terminally amidated. The cDNA encoding the leginsulin was cloned, sequenced and considered to code for a precursor polypeptide consisting of a putative signal peptide, the leginsulin, a linker peptide, a 6-kDa peptide and a C-terminal peptide. Although there is no sequence similarity between the leginsulin and insulin or insulin-like growth factors, the leginsulin is a possible candidate for plant peptide hormones.
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PMID:A peptide that stimulates phosphorylation of the plant insulin-binding protein. Isolation, primary structure and cDNA cloning. 807 38

GAP-43 isolated from calf brain was analyzed by the electrospray mass spectrometry. The mass spectrum of the intact protein showed two species with a mass difference of 80 Da, suggesting that the isolated GAP-43 contains phosphorylated species. To establish the in vivo phosphorylation sites, the protein was digested with trypsin, and analyzed by the liquid chromatography/mass spectrometry technique, in which a capillary reversed-phase chromatography column was connected on line to an electrospray mass spectrometer. Two pairs of peptides with a mass difference of 80 Da were observed. From the tandem mass spectrometry, two novel phosphorylation sites (Thr-87 and Ser-152) were identified. The novel phosphorylation sites contain proline immediately after the phosphorylated serines. No phosphorylated peptide was detected corresponding to the protein kinase C or casein kinase II phosphorylation sites. A peptide corresponding to the acetylated N-terminal peptide was also identified. The mass of the peptide suggests that the 2 cysteinyl residues are not palmitoylated but form a disulfide bridge.
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PMID:A mass spectrometric study on the in vivo posttranslational modification of GAP-43. 807 93

1. A novel tridecapeptide was isolated from extracts of bovine adrenal medulla chromaffin vesicles and the primary structure determined to be SVPHFSDEDKDPE. 2. This peptide is identical to the C termini of human and porcine 7B2 and is highly homologous to the same region of the mouse and Xenopus lavis protein. 3. In all these species the homologous peptide is preceded by a pair of lysine residues, a potential proteolytic processing site. 4. Ser6 is part of a well-conserved casein kinase II consensus phosphorylation sequence. Evidence for phosphorylation of this residue was obtained during Edman sequencing. 5. Thus, this novel adrenal medullary probably arises from the posttranslational processing of the bovine 7B2 protein.
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PMID:Identification of a 7B2-derived tridecapeptide from bovine adrenal medulla chromaffin vesicles. 824 90

Smooth muscle caldesmon was phosphorylated by casein kinase II, and the effects of phosphorylation on the interaction of caldesmon and its chymotryptic peptides with myosin and tropomyosin were investigated. The N-terminal chymotryptic peptide of caldesmon of molecular mass 27 kDa interacted with myosin. Phosphorylation of Ser-73 catalysed by casein kinase II resulted in a 2-fold decrease in the affinity of the native caldesmon (or its 27 kDa N-terminal peptide) for smooth muscle myosin. At low ionic strength, caldesmon and its N-terminal peptides of molecular masses 25 and 27 kDa were retarded on a column of immobilized tropomyosin. Phosphorylation of Ser-73 led to a 2-4-fold decrease in the affinity of caldesmon (or its N-terminal peptides) for tropomyosin. Thus phosphorylation of Ser-73 catalysed by casein kinase II affects the interaction of caldesmon with both smooth muscle myosin and tropomyosin.
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PMID:Phosphorylation by casein kinase II affects the interaction of caldesmon with smooth muscle myosin and tropomyosin. 845 32


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