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)

The predicted protein kinase activity of the cloned gene product of the human myotonic dystrophy locus has been experimentally verified. Affinity-purified recombinant DM protein kinase became phosphorylated itself and transphosphorylated histone H1. These activities were not present in the bacterial host cells and were exhibited by DMPK and DMPKH, recombinant proteins which contain the protein kinase domain but exhibit distinct sizes, 43 and 66 kDa, respectively. DMPKH was further purified by velocity sedimentation on sucrose gradients; both activities migrated with the recombinant protein at 41 S, consistent with discrete multimeric particles. Phosphoamino acid analysis showed that threonine (predominantly) and serine were phosphorylated in both DMPKH and histone H1. Although PKA and PKC are the known types of protein kinase with closest sequence homology to the DM protein kinase domain, purified DMPKH was inhibited by 4 mM but not 0.04-0.4 mM H7 and H8, which inhibit PKA and PKC with Ki's of 0.4-15 microM. Specific inhibitors of other classes of multifunctional serine/threonine protein kinases such as casein kinases I (CKI-7) and II (heparin) and calcium/calmodulin-dependent protein kinase II (KN-62) did not inhibit DMPKH. DMPKH did not phosphorylate membrane-associated phosphoproteins such as acetylcholine receptor or spectrin which are known to be substrates for PKA, PKC, and CKI and -II, respectively. These experimental results suggest that the active center of the recombinant human myotonic dystrophy protein kinase may have properties distinct from the well-studied classes of serine/threonine protein kinases, in contrast to predictions based upon primary structure alone.
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PMID:Phosphorylation reactions of recombinant human myotonic dystrophy protein kinase and their inhibition. 807 83

The clinical manifestation of myotonic dystrophy (DM) is correlated to the extent of expansion of an unstable [CTG]n DNA motif. Recent studies have demonstrated that this trinucleotide motif forms part of the last, 3' untranslated exon of a gene which potentially encodes multiple protein isoforms of a serine/threonine protein kinase (myotonic dystrophy protein kinase, DM-PK). We report here on the development of antisera against synthetic DM-PK peptide antigens and their use in biochemical and histochemical studies. Immunoreactive DM-kinase protein of 53 kD is present at low levels in skeletal and cardiac muscle extracts of DM patients and normal controls. Immunohistochemical staining revealed that DM-PK is localised prominently at sites of neuromuscular and myotendinous junctions (NMJs and MTJs) of human and rodent skeletal muscles. Furthermore, very low levels of immunoreactive DM-PK protein are present in the sarcoplasm of predominantly type I fibres in various muscles. Strikingly, presence of the protein can also be demonstrated for NMJs of muscular tissues of adult and congenital cases of DM, with no gross changes in structural organisation. Our findings provide a basis for further characterisation of the role of the kinase in protein assembly processes or signal mediation at synaptic sites and ultimately for the understanding of the complex pathophysiology of DM.
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PMID:Myotonic dystrophy kinase is a component of neuromuscular junctions. 828 Nov 52

The most common adult form of muscular dystrophy, myotonic dystrophy, is due to a triplet repeat (CTG) expansion in the 3' untranslated region of the myotonic dystrophy gene. Although this gene is known to encode a protein kinase, the mechanism by which a defect in this gene results in a disease state is not understood. To gain insight into this mechanism, the yeast two hybrid system was utilized to identify proteins which interact with myotonic dystrophy protein kinase. Eight positive clones were identified that interact specifically with the myotonic dystrophy protein kinase. One clone, which encodes a novel protein interacting with myotonic dystrophy protein kinase both in vivo in yeast and in vitro, was characterized further. The gene encoding this protein may represent a member of a small gene family, and the protein (95 amino acids) exhibits a high degree of homology to an snRNP protein, D1. This novel protein may be a member of the signal transduction pathway which is responsible for the manifestation of this disease.
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PMID:Identification of a novel protein, DMAP, which interacts with the myotonic dystrophy protein kinase and shows strong homology to D1 snRNP. 885 85

We have cloned a novel serine/threonine protein kinase (PK428) which is highly related (65%) within the kinase domain to the myotonic dystrophy protein kinase (DM-PK), as well as the cyclic AMP-dependent protein kinase (33%). Northern blots demonstrate that PK428 mRNA is distributed widely among tissues and is expressed at the highest levels in pancreas, heart, and skeletal muscle, with lower levels in liver and lung. Two PK428 mRNAs 10 and 3.8 kilobase pairs in size are seen in a number of cell lines, including hematopoietic and breast cancer cells. An antibody generated to a glutathione S-transferase-PK428 fusion protein detects a 65-kDa protein in these cell lines, and a similarly sized protein when the cloned cDNA is transiently expressed in Cos 7 cells. Immunoprecipitation of the transiently expressed PK428 protein and incubation with [gamma-32P]ATP demonstrate that it is capable of autophosphorylation. In addition, immunoprecipitates of the PK428 protein kinase also phosphorylated histone H1 and a peptide encoding a cyclic AMP-dependent protein kinase substrate. The gene corresponding to the 3.8-kb PK428 mRNA, and its corresponding 65-kDa protein, was isolated by polymerase chain reaction screening of a P1 phage human genomic library. Using this P1 phage clone as a probe, the PK428 gene was located on 1q41-42, a possible location for a human senescence gene, a gene associated with Rippling muscle disease, as well as a region associated with genetically acquired mental retardation.
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PMID:Cloning and chromosomal location of a novel member of the myotonic dystrophy family of protein kinases. 909 43

The small GTPases Cdc42 and Rac regulate a variety of biological processes, including actin polymerization, cell proliferation, and JNK/mitogen-activated protein kinase activation, conceivably via distinct effectors. Whereas the effector for mitogen-activated protein kinase activation appears to be p65PAK, the identity of effector(s) for actin polymerization remains unclear. We have found a putative effector for Drosophila Cdc42, Genghis Khan (Gek), which binds to Dcdc42 in a GTP-dependent and effector domain-dependent manner. Gek contains a predicted serine/threonine kinase catalytic domain that is 63% identical to human myotonic dystrophy protein kinase and has protein kinase activities. It also possesses a large coiled-coil domain, a putative phorbol ester binding domain, a pleckstrin homology domain, and a Cdc42 binding consensus sequence that is required for its binding to Dcdc42. To study the in vivo function of gek, we generated mutations in the Drosophila gek locus. Egg chambers homozygous for gek mutations exhibit abnormal accumulation of F-actin and are defective in producing fertilized eggs. These phenotypes can be rescued by a wild-type gek transgene. Our results suggest that this multidomain protein kinase is an effector for the regulation of actin polymerization by Cdc42.
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PMID:Genghis Khan (Gek) as a putative effector for Drosophila Cdc42 and regulator of actin polymerization. 937 83

The subcellular localization of myotonic dystrophy protein kinase has been examined in human cardiac muscles with confocal laser-scanning microscopy and electron microscopy. A polyclonal antibody was produced against the synthesized peptide from a human kinase cDNA clone. We checked the antibody specificity for cardiac myotonic dystrophy protein kinase using an immunoblotting technique. Immunoblotting of extract from human cardiac muscles showed mainly 70 kDa and 55 kDa molecular weight bands. Confocal images of the protein kinase immunostaining showed striated banding patterns similar to those of skeletal muscles. In addition, the kinase was strongly detected around the intercalated disc. Immunoelectron microscopy showed that the kinase was mainly expressed in both corbular and junctional sarcoplasmic reticulum, but not in network sarcoplasmic reticulum. These results suggest that myotonic dystrophy protein kinase may be involved in the modulation of Ca2+ homeostasis in cardiac myofibres.
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PMID:Immunolocalization of myotonic dystrophy protein kinase in corbular and junctional sarcoplasmic reticulum of human cardiac muscle. 961 Aug 15

The p21 GTPases, Rho and Cdc42, regulate numerous cellular functions by binding to members of a serine/threonine protein kinase subfamily. These functions include the remodeling of the cell cytoskeleton that is a feature of cell growth and differentiation. Two of these p21 GTPase-regulated kinases, the myotonic dystrophy protein kinase-related Cdc42-binding kinases (MRCKalpha and beta), have been recently characterized in rat. Both of these proteins phosphorylate nonmuscle myosin light chain, a prerequisite for the activation of actin-myosin contractility. Here we report the cDNA cloning of the human homologue of MRCKbeta, CDC42BPB, which was found by Northern blot analysis to be expressed in a wide range of tissues. The human CDC42BPB gene maps to cytogenetic band 14q32.3 by FISH analysis.
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PMID:Cloning and chromosomal localization of human Cdc42-binding protein kinase beta. 1019 71

The genetic abnormality in myotonic muscular dystrophy, multiple CTG repeats lie upstream of a gene that encodes a novel protein kinase, myotonic dystrophy protein kinase (DMPK). Phospholemman (PLM), a major membrane substrate for phosphorylation by protein kinases A and C, induces Cl currents (I(Cl(PLM))) when expressed in Xenopus oocytes. To test the idea that PLM is a substrate for DMPK, we measured in vitro phosphorylation of purified PLM by DMPK. To assess the functional effects of PLM phosphorylation we compared I(Cl(PLM)) in Xenopus oocytes expressing PLM alone to currents in oocytes co-expressing DMPK, and examined the effect of DMPK on oocyte membrane PLM expression. We found that PLM is indeed a good substrate for DMPK in vitro. Co-expression of DMPK with PLM in oocytes resulted in a reduction in I(Cl(PLM)). This was most likely a specific effect of phosphorylation of PLM by DMPK, as the effect was not present in oocytes expressing a phos(-) PLM mutant in which all potential phosphorylation had been disabled by Ser --> Ala substitution. The biophysical characteristics of I(Cl(PLM)) were not changed by DMPK or by the phos(-) mutation. Co-expression of DMPK reduced the expression of PLM in oocyte membranes, suggesting a possible mechanism for the observed reduction in I(Cl(PLM)) amplitude. These data show that PLM is a substrate for phosphorylation by DMPK and provide functional evidence for modulation of PLM function by phosphorylation.
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PMID:Phospholemman is a substrate for myotonic dystrophy protein kinase. 1081 36

Myotonic dystrophy (DM1) is an autosomal dominant neuromuscular disorder associated with a (CTG)(n) expansion in the 3'-untranslated region of the DM1 protein kinase (DMPK) gene. To explain disease pathogenesis, the RNA dominance model proposes that the DM1 mutation produces a gain-of-function at the RNA level in which CUG repeats form RNA hairpins that sequester nuclear factors required for proper muscle development and maintenance. Here, we identify the triplet repeat expansion (EXP) RNA-binding proteins as candidate sequestered factors. As predicted by the RNA dominance model, binding of the EXP proteins is specific for dsCUG RNAs and proportional to the size of the triplet repeat expansion. Remarkably, the EXP proteins are homologous to the Drosophila muscleblind proteins required for terminal differentiation of muscle and photoreceptor cells. EXP expression is also activated during mammalian myoblast differentiation, but the EXP proteins accumulate in nuclear foci in DM1 cells. We propose that DM1 disease is caused by aberrant recruitment of the EXP proteins to the DMPK transcript (CUG)(n) expansion.
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PMID:Recruitment of human muscleblind proteins to (CUG)(n) expansions associated with myotonic dystrophy. 1097 Aug 38

Myotonic dystrophy (DM1) is the most common form of adult muscular dystrophy and is inherited as an autosomal dominant trait. The genetic basis of DM1 is the expansion of a CTG repeat in the 3' untranslated region of a protein kinase gene (DMPK). The molecular mechanism by which this expanded repeat produces the pathophysiology of DM1 remains unknown. Transcripts from the expanded allele accumulate as foci in the nucleus of DM1 cells and it has been suggested that these transcript foci sequester cellular proteins that are required for normal nuclear function. We have investigated the role of three RNA-binding proteins, CUG-BP, hnRNP C and MBNL, as possible sequestered factors. Using a combination of indirect immunofluorescence to detect endogenous proteins and overexpression of proteins with green fluorescent protein (GFP) tags we have shown that CUG-BP and hnRNP C do not co-localise with expanded repeat foci in DM1 cell lines. However, GFP-tagged MBNL does itself form foci in DM1 cell lines and co-localises with the foci of expanded repeat transcripts. GFP-tagged MBNL does not appear as foci in non-DM1 cell lines. This work provides further support for the involvement of MBNL in DM1.
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PMID:In vivo co-localisation of MBNL protein with DMPK expanded-repeat transcripts. 1143 21


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