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)

A gelatin-binding glycoprotein from L6 rat myoblasts, designated gp46, was shown to be phosphorylated in vivo. This phosphorylation was increased slightly (18%) by phorbol ester treatment of L6 suggesting protein kinase C involvement. Purified gp46 could be phosphorylated in vitro with protein kinase C, but not by the catalytic subunit of cAMP-dependent protein kinase. Comparison of the phosphotryptic peptide maps of in vitro and in vivo labeled gp46 suggested that in vivo phosphorylation of gp46 may be mediated by protein kinase C.
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PMID:Phosphorylation of a gelatin-binding protein from L6 myoblasts by protein kinase C. 359 66

A cell surface antigen expressed in association with cell proliferation was detected and identified as a glycoprotein of molecular weight of 125,000 (gp 125) by using monoclonal antibodies against human or rat bladder cancer cells. We have found that appearance of the antigen in stimulated lymphocytes precedes the emergence of interleukin 2 receptor and that it is regulated by Ca ion and protein kinase-C.
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PMID:[Properties of glycoprotein 125, a proliferation-associated cell surface antigen]. 360 41

Phospholamban, the cardiac sarcoplasmic reticulum proteolipid, is phosphorylated by cAMP-dependent protein kinase, by Ca2+/phospholipid-dependent protein kinase, and by an endogenous Ca2+/calmodulin-dependent protein kinase, the identity of which remains to be defined. The aim of this study was therefore to characterize the latter kinase, called phospholamban kinase. Phospholamban kinase was purified approximately 42-fold with a yield of 11%. The purified fraction exhibits a specific activity of 6.5 nmol of phosphate incorporated into exogenous phospholamban per minute per milligram of protein. Phospholamban kinase appears to be a high molecular weight enzyme and presents a broad substrate specificity, synapsin-1, glycogen synthase, and smooth muscle myosin regulatory light chain being the best substrates. Phospholamban kinase phosphorylates synapsin-1 on a Mr 30 000 peptide. The enzyme exhibits an optimum pH of 8.6, a Km for ATP of 9 microM, and a requirement for Mg2+ ions. These data suggest that phospholamban kinase might be an isoenzyme of the multifunctional Ca2+/calmodulin-dependent protein kinase. Consequently we have searched for Mr 50 000-60 000 phosphorylatable subunits among cardiac sarcoplasmic reticulum proteins. A Mr 56 000 protein was found to be phosphorylated in the presence of Ca2+/calmodulin. Such phosphorylation alters the electrophoretic migration velocity of the protein. In addition, this protein that binds calmodulin was always found to be present in fractions containing phospholamban kinase activity. This Mr 56 000 protein is therefore a good candidate for being a subunit of phospholamban kinase. However, the Mr 56 000 calmodulin-binding protein and the Mr 53 000 intrinsic glycoprotein which binds ATP are two distinct entities.
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PMID:Characterization and partial purification of cardiac sarcoplasmic reticulum phospholamban kinase. 373 Mar 67

The receptor for epidermal growth factor (EGF) is a 170,000-180,000 molecular weight single-chain glycoprotein of 1,186 amino acids. Its sequence suggests that it has an external EGF-binding domain, formed by the NH2-terminal 621 amino acids, linked to a cytoplasmic region by a single membrane-spanning segment. In the cytoplasmic portion, starting 50 residues from the membrane, there is a 250-residue stretch similar to the catalytic domain of the src gene family of retroviral tyrosine protein kinases, and, indeed, a tyrosine-specific protein kinase activity intrinsic to the receptor is stimulated when EGF is bound. Increased tyrosine phosphorylation of cellular proteins, detected in A431 cells following EGF binding, may be important in the mitogenic signal pathway. Tumour promoters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA), counteract this increase, as well as causing loss of a high affinity class of EGF binding sites. The major receptor for TPA has been identified as the serine/threonine-specific Ca2+/phospholipid-dependent diacylglycerol-activated protein kinase, protein kinase C. By substituting for diacylglycerol, TPA stimulates protein kinase C. Protein kinase C phosphorylates purified EGF receptor at specific sites, and this reduces EGF-stimulated tyrosine protein kinase activity. TPA treatment of A431 cells increases serine and threonine phosphorylation of the EGF receptor at the same sites, which suggests that the reduction of EGF receptor kinase activity in TPA-treated cells is a consequence of the receptor's phosphorylation by the kinase. We have attempted to identify these phosphorylation sites and show here that protein kinase C phosphorylates threonine 654 in the human EGF receptor. This threonine is in a very basic sequence nine residues from the cytoplasmic face of the plasma membrane in the region before the protein kinase domain; it is thus in a position to modulate signalling between this internal domain and the external EGF-binding domain.
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PMID:Protein kinase C phosphorylation of the EGF receptor at a threonine residue close to the cytoplasmic face of the plasma membrane. 609 Sep 44

Gallo and his coworkers isolated a retrovirus (HTLV) from human cells derived from T-cell leukemia and lymphoma. Hinuma and his coworkers isolated independently a similar virus from a cell line derived from adult T-cell leukemia (ATL) patient. The occurrence of ATL correlates with the formation of antibody to ATL associated antigens or ATLA. To understand the etiological relationship between ATL and HTLV, we analyzed the antigens termed ATLA and found that they are polypeptides encoded by HTLV genome. We further studied the genome of HTLV and its gene expression in cells as well as in a cell-free translation system. We focused on a defective type HTLV produced from a cell line MT-2 that transforms normal lymphocytes most efficiently. The 24S defective gene of HTLV consists of a fused gene of gag-pXs and is amplified at the proviral state. The in vitro translation experiments revealed that the 24S defective gene of HTLV directs the synthesis of p28 of ATLA. By the sequence analysis of the amplified gag-pXs fused genes, we found that a carboxy terminal portion of p28 is translated from a pX-0 region. We further investigated a function of the gag-pX-0 fusion protein, p28. The p28 has an associated protein kinase activity that requires manganese instead of magnesium and phosphorylates the serine residue specifically. Another defective HTLV with a genomic 32S RNA was analyzed. The 32S defective genomic RNA forms a subgenomic 20S RNA in cells. The 20S mRNA is a transcript of an env-pXs fused genome and directs the synthesis of a fused glycoprotein, gp68 of ATLA. The sequence analysis of a cloned cDNA derived from the subgenomic 20S mRNA revealed that a coding frame of the entire pX-IV region is translated. In fact, an antibody against synthetic polypeptides of the pX-IV, immunoprecipitated the gp68. These results demonstrate at the first time that the pX-0 and pX-IV of HTLV genome are expressed in human cells. The biological activities of the fused pXs proteins are also discussed. Human T-cell leukemia virus type I (HTLV-I), a family of human retrovirus and the predicted causative agent of human adult T-cell leukemia/lymphoma (ATL) consists of the gag, pol, env, and pX regions (1).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The pX region of HTLV-I. 610 Jun 40

Myelin isolated from the peripheral (PNS) and central nervous system (CNS) of mouse contained a protein kinase which catalyzed phosphorylation of myelin proteins. In the case of CNS myelin, small and large basic proteins were phosphorylated whereas in the case of PNS myelin, a glycoprotein (Po) as well as other basic proteins (P1 and P2) were phosphorylated. Ca2+, but not adenosine 3',5'-monophosphate (cyclic AMP), markedly (5- to 10-fold) stimulated phosphorylation of PNS and CNS myelin proteins. There was no difference between the normal and dystrophic mouse CNS myelin phosphorylation. However, a marked decrease in the cauda equina PNS myelin phosphorylation ofthe dystrophic mouse was observed. Interestingly, the dystrophic sciatic nerve myelin phosphorylation, compared to normal, was higher.
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PMID:Calcium ion stimulated endogenous protein kinase catalyzed phosphorylation of peripheral and central nerve myelin proteins: comparison between normal and genetically dystrophic mouse. 615 63

The transformation-specific protein pp60(src) coded for by avian sarcoma viruses and its associated protein kinase activity is present in virus particles of Rous sarcoma virus, Schmidt-Ruppin strain, subgroup D. Quantitative comparison of the immunoglobulin G-phosphorylating activity in Schmidt-Ruppin D virus and Schmidt-Ruppin D virus-transformed fibroblasts indicated that there was two- to fourfold less activity in the virus particles. Disruption of virus particles with nonionic detergent demonstrated that the protein kinase activity fractionated together with the viral membrane protein gp85. Therefore, viral membranes were isolated by floating detergent-disrupted virus through a discontinuous sucrose density gradient. At a characteristic density corresponding to 26% sucrose, viral membranes were identified by the radioactively labeled viral glycoprotein and furthermore by the membrane marker enzyme Na(+)-K(+)-stimulated, Mg(2+)-activated ATPase and were visualized by electron microscopy. Contamination by cell membranes could be ruled out, since (i) the virus preparation was free of cell membrane contaminants as judged from electron microscopy, (ii) floating of intact virus did not release membraneous material, and (iii) virus-free tissue culture fluid from Schmidt-Ruppin D virus-transformed nonproducer cells (which potentially contain cell membranes) did not contribute any immunoglobulin G-phosphorylating activity after mixing with nontransforming virus and pelleting it. Both pp60(src) and the protein kinase activity were found to be associated with the viral membrane. Solubilization of virus by detergent released two phosphoproteins, with molecular weights of 42,000 and 45,000 which reacted with sera specific for pp60(src) and revealed protein kinase activity but which were not membrane bound and may have represented degradation products of pp60(src). Surface iodination of intact virus particles (harvested at 3-h intervals) did not result in radioactive labeling of pp60(src), whereas collection at 24-h intervals allowed iodination of pp60(src). In contrast to the viral glycoprotein gp85, the iodinated virion-associated pp60(src) was insensitive to mild proteolytic treatment. Binding to tumorbearing-rabbit serum, immunoglobulin G phosphorylation, and endogenous phosphorylation of 60,000-, 45,000-and 42,000-dalton proteins required lysed virus and were not possible with intact virus. These results indicated that pp60(src) was embedded within the viral membrane. Membrane proteins phosphorylated in vitro were analyzed for their phosphoamino acid composition. Eight polypeptides exhibited phosphorylation in tyrosine and were absent in nontransforming viral controls.
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PMID:Association of the transformation-specific protein pp60src with the membrane of an avian sarcoma virus. 626 49

Epidermal Growth Factor (EGF) is a 6045 dalton polypeptide which stimulates the proliferation of various cell types in vitro and in vivo. EGF binds to diffusely distributed membrane receptors which rapidly cluster primarily on coated pits areas on the plasma membrane. Subsequently, the EGF-receptor complexes are endocytosed and degraded by lysosomal enzymes. The lateral diffusion coefficient (D) of EGF-receptor complexes on cultured cells increases gradually from D = 2.8 X 10(-10) cm2/sec at 5 degrees C to 8.5 X 10(-10) cm2/sec at 37 degrees C. In the same range of temperature the rotational correlation times change from 25 to 50 microseconds to approximately 350 microseconds. Hence, at 4 degrees C, the occupied EGF receptors translate and rotate rapidly in the plane of the membrane. At 37 degrees C, EGF receptors form microclusters composed of 10 to 50 molecules. Moreover, it is concluded that both at 4 degrees C and 37 degrees C lateral diffusion of the occupied receptors is not the rate determining step for either receptor clustering or internalization. EGF receptor is a 150,000 to 170,000 dalton glycoprotein. The receptor is in close proximity to an EGF-sensitive, cAMP-independent, tyrosine-specific protein kinase which also phosphorylates the receptor molecules itself. The EGF sensitive kinase is similar to the kinase activity which is associated with certain RNA tumor viruses. The fact that the non-mitogenic cyanogen-bromide cleaved EGF is as potent as native EGF in stimulating phosphorylation suggests that EGF-induced, protein phosphorylation is a necessary but insufficient signal for the induction of DNA synthesis by EGF. EGF receptor serves also as the binding site for Transforming Growth Factors (TGF) which compete with EGF and induce anchorage-independent growth of normal cells in soft agar. Tumor promoters such as phorbol ester effect the binding of EGF to its membrane receptors and its ability to stimulate DNA synthesis. EGF itself has also some tumor promoting activity. Hence, the membrane receptor for EGF seems to participate in the regulation of normal and neoplastic growth. Monoclonal antibodies against EGF receptor (IgM) induce various early and delayed effects of EGF, while their monovalent Fab' fragments are devoid of biological activity. These observations support the notions that EGF receptor rather than EGF itself is the active moiety and that the role of the hormone is to perturb the receptor in the appropriate way, probably by inducing the microaggregation of EGF receptors.
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PMID:Regulation of cell proliferation by epidermal growth factor. 630 52

1. The phosphorylation by cAMP and protein kinase I of rat cardiac sarcolemma (SL) and sarcoplasmic reticulum (SR) isolated from the same homogenate, was compared. 2. In both fractions, the phosphate incorporation is strongly dependent on the ATP and the membrane protein concentration. 3. SDS-gel electrophoresis reveals that in the SL preparation a protein of Mr = 24,500 and a glycoprotein of Mr = 17,500 are mainly phosphorylated, while in the SR fraction the main phosphate incorporation is found in a protein having a Mr = 37,000. 4. Isoprenaline stimulates the phosphorylation of SL but not of SR. Propranolol abolished that stimulatory action of isoprenaline completely, suggesting that the beta-adrenoceptor is involved.
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PMID:Comparison of cyclic AMP-dependent phosphorylation of sarcolemma and sarcoplasmic reticulum from rat cardiac ventricle muscle. 630 38

Synaptic junctions (SJs) isolated from rat brain are associated with protein kinase activity and a unique complement of high molecular weight gglycoproteins. Incubation of SJs with [gamma-32P]A+ glycoproteins which were retained by concanavalin A agarose (con A+ glycoproteins). Three major (apparent mol. wt. 180 K, 130 K and 110 K) and 2 minor (apparent mol. wt. 230 K and 145 K) glycoproteins were identified in the con A+ fraction. Of these, GP180 incorporated the most 32P and GP145 was not labeled. Peptide mapping experiments showed that each molecular weight class of glycoprotein was associated with a unique set of phosphorylated peptides. Cyclic AMP stimulated the incorporation of 32P into total SJ proteins and con A+ lycoproteins by 38% and 58%, respectively. GP130 showed the greatest increase in labelling in the presence of cyclic AMP (198% of control levels) although incorporation into all 4 glycoproteins was increased. Cyclic AMP selectively stimulated the incorporation of 32P into only 2 of the 6 phosphorylated peptides derived from GP130. These studies demonstrate that endogenous glycoproteins serve as substrates for intrinsic SJ protein kinases and identify this reaction as a potential means of modifying postsynaptic membrane function.
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PMID:Synaptic junctional glycoproteins are phosphorylated by cyclic-AMP-dependent protein kinase. 630 21


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