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)

We have identified and purified from bovine brain a novel protein kinase which catalyzes in vitro phosphorylation of neurofilament proteins NF-H and NF-M and tau proteins at sites implicating the enzyme in the regulation of neurocytoskeleton dynamics and in Alzheimer pathology. The protein kinase displays a phosphorylation site specificity similar or identical to the cell cycle regulatory kinase, cdc2 kinase. The purified kinase is a heterodimer of a cdc2-like catalytic subunit, called cdk5, and a 25 kDa regulatory subunit. The regulatory subunit is essential for kinase activity, and it is derived from a 35 kDa protein, p35 by proteolysis. Northern blot analysis of tissue distribution indicates that cdk5 is widely distributed but especially rich in brain, whereas p35 expression is only found in brain. The protein kinase is therefore termed neuronal cdc2-like kinase. The neuron-specificity of the enzyme appears to be conferred by the regulatory subunit. During cell division, cdc2 kinase is regulated by complex phosphorylation mechanisms involving a network of specific protein kinases. Some of these kinases or their homologs have been found in mammalian brains and they may be involved in the regulation of neuronal cdc2-like kinase.
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PMID:Structure, function, and regulation of neuronal Cdc2-like protein kinase. 756 36

An open reading frame (ORF) with strong homology to eukaryotic serine/threonine protein kinases was found in the two Chlorella viruses SC-1A and PBCV-1. The deduced molecular weights of each putative protein kinase were 35 kDa and the predicted amino acid sequences of the two proteins were 95% identical. The ORF encoding the SC-1A protein kinase was over-expressed as a fusion protein in Escherichia coli. The recombinant fusion protein had autophosphorylation activity and could phosphorylate certain exogenous proteins. Antiserum against the recombinant fusion protein reacted with a 35 kDa protein plus three larger proteins from virus infected cells. The 35 kDa protein was a late protein; however, the 35 kDa protein was not packaged in the virion, even though virions contain protein kinase activity.
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PMID:Characterization of a protein kinase gene from two Chlorella viruses. 778 17

In the retinas of teleost fish dopamine, released from interplexiform cells, modulates synaptic transmission at both the chemical and electrical synapses of retinal horizontal cells. This modulation is due to activation of adenylate cyclase and phosphorylation by protein kinase A, perhaps of the synaptic ion channel proteins themselves. In this study we have fractionated the white perch retina by Percoll density gradient centrifugation in order to identify proteins which coenrich with horizontal cells. In addition we have tested retinal fractions for phosphorylation by native cAMP-dependent kinase. Our findings indicate that there are at least 3 proteins of molecular weights 28, 43/44 and 50 kDa which coenrich with horizontal cells and 3 proteins of 30/31 kDa, 35 kDa (putative rhodopsin) and 48 kDa (putative arrestin) which coenrich with photoreceptor fractions. The 43/44 kDa phosphoprotein is a target for cAMP-dependent protein phosphorylation and thus is apparently an element of the dopaminergic modulatory pathway in perch horizontal cells.
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PMID:Protein content and cAMP-dependent phosphorylation of fractionated white perch retina. 782 Jun 51

Xenopus p53 cDNA, homologous to the human tumour suppressor p53, has previously been cloned from oocyte and gastrula libraries. In this report, we describe a polyclonal antibody 2674 raised against Xenopus p53 (Xp53) expressed in bacteria, that recognises proteins of approximately 52, 46 and 35 kDa present in Xenopus oocytes, parthenogenically activated eggs and in somatic tissue culture cells. We report here purification of Xp53 from insect cells infected with Xp53-baculovirus, and this protein is shown to be phosphorylated by casein kinase II but has low sequence-specific DNA binding activity. Using similar purification conditions, we have isolated endogenous Xp53, showing that Xenopus eggs contain high levels of p53 protein. Xp53 from eggs binds to the p53-specific DNA-binding consensus sequence. Two dimensional gel analysis indicates that Xp53 from eggs may exist in various states of phosphorylation. u.v.-induced DNA damage of somatic Xenopus cells results in accumulation of Xp53. We suggest that the high levels of putative Xp53 detected in eggs may represent maternal stockpiles of a protein necessary to protect rapidly dividing cells from the effects of DNA damage.
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PMID:Xenopus p53 is biochemically similar to the human tumour suppressor protein p53 and is induced upon DNA damage in somatic cells. 808 98

In teleost retinas, rods elongate in the light and shorten in the dark. Rod motility is mediated by the actin cytoskeleton of the inner segment and is regulated by cyclic AMP- or cyclic GMP-stimulated phosphorylation of target proteins. In this study, we have identified the target proteins of cyclic nucleotide-dependent kinases in rods, using preparations of isolated, motile rod inner-outer segments (RIS-ROS). Five proteins found in Percoll-purified RIS-ROS were phosphorylated in the presence of cAMP (> 10 nM), cGMP (> or = 10 microM) and exogenous catalytic subunit of cAMP-dependent protein kinase (PKA). The PKA inhibitor, PKI, blocked stimulation of phosphorylation by both cAMP and cGMP. Three cAMP-stimulated phosphoproteins were detected in cytoskeletal fractions of light- and dark-adapted RIS-ROS. One of these, PP33, appears to be a fish homologue of mammalian phosducin, based on immunolabeling by two different antibodies against mammalian phosducin and on electrophoretic characteristics in 2-D gels. Two additional phosducin immunoreactive bands were detected in Western blots. One, at 35 kDa, comigrated with a second cAMP-stimulated RIS-ROS phosphoprotein, PP35, which was also detected in the cytoskeleton. The other, at 37 kDa, was present in whole teleost retinas but not in purified RIS-ROS. Our results suggest that the effects of both cAMP and cGMP on teleost rod motility are mediated through PKA modulation of target phosphoproteins. These phosphoproteins include a cytoskeleton-associated phosducin homologue.
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PMID:Identification of cyclic nucleotide-regulated phosphoproteins, including phosducin, in motile rod inner-outer segments of teleosts. 815 21

The activin-binding protein, follistatin (FS), was immunoprecipitated from metabolically labeled rat anterior pituitary cells or their media using a specific antiserum to purified porcine FS (anti-FS). Several immunoreactive proteins, including one that had a mobility in the range of 42-44 kilodaltons (kDa), were detected in the cell lysates. When immunoprecipitates of the culture medium were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, a broad 35- to 46-kDa or 39- to 53-kDa band was visualized under unreducing or reducing conditions, respectively. Upon deglycosylation by treatment with N-glycosidase-F, the secreted product migrated as a sharp protein band with an apparent size of 35 kDa. The identity or the relatedness of the immunoprecipitated proteins to FS was verified by the ability of the C-terminally truncated form of recombinant human FS (rhFS288) to compete for binding to anti-FS. When the cultured rat anterior pituitary cells were treated with either forskolin or 12-O-tetradecanoylphorbol acetate, the accumulation of FS in the culture medium was stimulated by approximately 2.5-fold. These observations suggest that the activation of either the protein kinase A or the protein kinase C signaling pathway has a stimulatory effect on anterior pituitary FS production. A more dramatic stimulation of FS secretion (up to 7-fold) was observed when the rat anterior pituitary cells were treated with activin-A. The concentration dependence for this effect was within the same range that has been reported for most of the actions of activin-A. Inhibin-A suppressed basal FS secretion and blocked its stimulation by activin-A. To determine if locally produced FS exerts an influence on the response of gonadotropes to activins, the effects of anti-FS on FSH secretion were monitored. The ability of this FS antiserum to immunoneutralize the activity of FS was initially confirmed; anti-FS attenuated the inhibitory action of exogenous follistatin on FSH secretion. Treatment of cells with the antiserum increased the apparent sensitivity of gonadotropes to submaximal concentrations of activin-A. Moreover, the presence of the antiserum lowered the concentration of activin-A that was required to produce the maximum amount of FSH secretion, without changing the magnitude of the response. These results suggested that locally produced FS interferes with the secretory response of gonadotropes to activins. Changes in locally secreted FS may, therefore, represent a mechanism by which the response of rat anterior pituitary cells to incoming stimuli are tightly regulated.
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PMID:Activin-A regulates follistatin secretion from cultured rat anterior pituitary cells. 824 77

The effect of androgen on protein kinase activities was studied in chromosomal proteins from female mouse submandibular gland. The protein kinase activities in the nuclei were stimulated 3 h after testosterone administration. The in vitro addition of cAMP in the nuclei resulted in the enhancement of the androgen-sensitive protein kinase activities. SDS-PAGE analysis revealed that nonhistone proteins having molecular weights of 20-30 kDa and around 43 kDa were phosphorylated after androgen treatment. The addition of cAMP stimulated phosphorylation of nonhistone proteins having molecular weights with 15-25 kDa, 30 kDa and 35 kDa and the intensity of phosphorylation of these nonhistone proteins was enhanced after androgen treatment. These results suggest that androgen-sensitive protein kinases including cAMP-dependent protein kinase were present and that phosphorylation of nonhistone proteins by these protein kinases may be involved in mediating androgen-induced gene activation.
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PMID:cAMP-dependent phosphorylation of nuclear proteins in mouse submandibular gland following testosterone administration. 839 74

The cytoplasmic tail of the human 300-kDa mannose 6-phosphate receptor (MPR 300-CT) is an excellent substrate for casein kinase II in vitro. The phosphorylated MPR 300-CT was cross-linked by means of bis(sulfosuccinimidyl)suberate mainly to a cytosolic protein of 35 kDa (referred to as TIP 35) and to 35- and 91-kDa proteins salt-washed from bovine brain membranes. Gel filtration suggested that TIP 35 is part of a higher molecular mass complex of approximately 130-150 kDa. Inhibition studies, using non-phosphorylated and phosphorylated MPR 300-CT and cross-linking, indicate that the interaction with TIP 35 is phosphorylation-specific. Furthermore, TIP 35 was only cross-linked to the MPR 300-CT phosphorylated by casein kinase II whereas the MPR 300-CT phosphorylated by protein kinase A failed to cross-link to TIP 35. These results indicate that the cytoplasmic tail of the MPR 300 interacts with a cytosolic protein depending on the phosphorylation by a casein kinase II-like kinase. The cross-linking with salt-washed membrane proteins, however, is inhibited by non-phosphorylated MPR 300-CT, suggesting that different structural determinants in the MPR 300-CT interact with cytosol- and membrane-derived proteins.
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PMID:Phosphorylation of the cytoplasmic tail of the 300-kDa mannose 6-phosphate receptor is required for the interaction with a cytosolic protein. 840 94

The cAMP-dependent protein-kinase-catalyzed phosphorylation of the two major intrinsic lens fiber cell plasma membrane proteins, MP20 and MP26, is likely restricted to the inner cortical and nuclear regions of the lens in vivo. The ovine-lens-specific connexin, MP70, that has been identified as Cx50 in mice and Cx45.6 in the chick, is also a protein kinase substrate although it does not appear to be phosphorylated by a number of protein kinases including cAMP-dependent protein kinase, calmodulin-dependent protein kinase or protein kinase C. Rather, an extrinsic lens membrane fraction was isolated which contained protein kinase activity that catalyzed the phosphorylation of MP70; this protein kinase activity was cAMP-independent, Ca(2+)-independent, Mg(2+)-dependent, phosphorylated MP70 on a serine residue(s) and migrated with a molecular mass of 35 kDa on a gel filtration column. Both MP70 phosphorylation and the endogenous protein kinase activity were restricted to the lens outer cortical region. This membrane-associated protein kinase activity represents the first reported partial characterization of an endogenous lens fiber cell protein kinase activity that catalyzes the phosphorylation of a lens connexin protein. The phosphatase-induced shift in the electrophoretic mobility of MP70 is not reversed by this protein kinase, indicating that MP70 is likely phosphorylated on different residues by two or more protein kinases.
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PMID:Characterization of the ovine-lens plasma-membrane protein-kinase substrates. 853 18

Cell membranes of the human epidermoid cell line A431 express classical bradykinin (BK) B2 receptors, as assessed by [3H]BK binding studies. Furthermore, stimulation by BK induced a time-dependent modulation of protein kinase C (PKC) activity in A431 cells: a rapid activation (t1/2 approximately 1 min) is followed by a slow inhibition (t1/2 approximately 20 min) of PKC translocation measured by [3H]phorbol 12,13-dibutyrate binding. In addition, BK stimulated both adenylate cyclase activity in A431 membranes and accumulation of intracellular cyclic AMP (cAMP) in intact cells in a retarded manner. A possible BK-induced activation of the cAMP pathway mediated via PKC, phospholipase D, prostaglandins or Ca2+/calmodulin was excluded. A 35 kDa protein was found in A431 membranes to be specifically phosphorylated in the presence of both BK and protein kinase A (PKA). An anti-alpha s-antibody, AS 348, abolished stimulation of adenylate cyclase activity in response to BK, cholera toxin and isoprenaline, strongly suggesting the involvement of Gs proteins in the BK action. The BK-activated cAMP signalling system might be important for the observed inactivation of PKC slowly evoked by BK: the BK-induced rapid activation of PKC is decreased by dibutyryl cAMP, and the slow inhibition of PKC is prevented by an inhibitor of PKA, adenosine 3':5'-monophosphothioate (cyclic, Rp isomer). The inhibition of PKC translocation might be exerted directly at the level of PKC activation, since stimulation of phosphoinositide hydrolysis by BK was affected by neither dibutyryl cAMP nor forskolin. Thus our results provide the first evidence that A431 cells BK is able to activate two independent signal-transduction pathways via a single class of B2 receptors but two different G proteins. The lagging stimulation of the cAMP signalling pathway via Gs might serve to switch off PKC, which is rapidly activated via Gq-mediated stimulation of phosphoinositide hydrolysis.
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PMID:Dual bradykinin B2 receptor signalling in A431 human epidermoid carcinoma cells: activation of protein kinase C is counteracted by a GS-mediated stimulation of the cyclic AMP pathway. 854 71


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