Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta-adrenergic receptor kinase (beta ARK) specifically phosphorylates the activated form of the beta 2-adrenergic receptor (beta 2AR) and related G protein-coupled receptors. To further elucidate the role of beta ARK in receptor desensitization, we generated a beta ARK dominant negative mutant by converting an invariant lysine residue in the protein kinase catalytic domain to an arginine. Expressed and purified beta ARK-K220R was able to inhibit wild type beta ARK phosphorylation of the beta 2AR in vitro. When stably transfected into human bronchial epithelial BEAS-2B cells, beta ARK-K220R promoted a > 2-fold increase in beta-agonist-stimulated cAMP production without affecting beta 2AR sequestration. In contrast, beta ARK-K220R had no effect on the desensitization of the prostaglandin E2 receptor response in BEAS-2B cells. These findings directly demonstrate a role for beta ARK in desensitization of the beta 2AR in intact cells and establish the potential utility of using dominant negative mutants to elucidate the substrate specificity of G protein-coupled receptor kinases.
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PMID:A beta-adrenergic receptor kinase dominant negative mutant attenuates desensitization of the beta 2-adrenergic receptor. 817 32

The nucleotide sequence of the helper component protease (HC-Pro) genes of three zucchini yellow mosaic virus (ZYMV) strains has been compared with that of a helper-deficient strain of ZYMV-HC. The comparisons revealed three unique deduced amino acid differences. Two of these mutations were located in regions which are conserved in other potyviruses. The role of these mutations in aphid transmissibility was examined by exchanging DNA fragments of part of the deficient HC-Pro gene with the respective section within the gene of the infectious full-length clone of the aphid-transmissible ZYMV. The first exchange included two of the three mutations, the first coding for a change from Asp to Gly (in a non-conserved region) and the second coding for a change from Arg to Ile [within the Phe-Arg-Asp-Lys (FRNK) conserved box]. This exchange resulted in a reduced transmission (20.6% for the mutated virus compared with 57.4% in the normal ZYMV when acquired from plants and 37.2% compared with 83.1%, respectively, when acquired from membranes). The second exchange incorporated a single mutation [conferring a change from Thr to Ala within the Pro-Thr-Lys (PTK) conserved box]. This single mutation resulted in almost total loss of HC activity in aphid transmission both from plants and from membranes. The Lys residue in the conserved Lys-Ile-Thr-Cys (KITC) box, which is related to loss of HC activity in potato virus Y, tobacco vein mottling virus and in the Michigan strain of ZYMV, is unchanged in the helper-deficient ZYMV. It is therefore proposed that more than one site in HC-Pro may be functionally related to aphid transmissibility. The possible reasons for the role of these mutations in helper activity in aphid transmission of ZYMV are discussed.
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PMID:Mutations in the helper component protease gene of zucchini yellow mosaic virus affect its ability to mediate aphid transmissibility. 820 4

A patient with liver cirrhosis who progressed to hepatocellular carcinoma was found to develop novel antinuclear antibodies. The serum was used to isolate full-length cDNA clones encoding related proteins of 530 amino acids (representative clone HCC1.4) and 524 amino acids (representative clone HCC1.3). Affinity-purified antibodies eluted from recombinant proteins recognized a 64-kD nuclear protein in Western blotting and decorated the nucleoplasm in a speckled-network fashion in immunofluorescence, colocalizing with antibodies to pre-mRNA splicing factor SC35 and uridine-rich small nuclear RNAs. The deduced amino acid sequence contained an arginine/serine-rich (RS) domain and three-ribonucleoprotein consensus sequence domains, two classes of motifs present in several splicing factors. A repeating octapeptide of Arg-Ser-Arg-Ser-Arg(Lys)-Glu(Asp)-Arg-Lys(Arg) was present in RS region of HCC1. This octapeptide sequence called RS-ERK motif was also found in splicing factors U2AF 35- and 65-kD proteins and 70-kD U1 small nuclear ribonucleoprotein. The molecular features and immunolocalization data suggest that the HCC1 autoantigen may be associated with splicing activities and are consistent with observations that autoantibody responses frequently target molecules involved in important cellular biosynthetic functions.
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PMID:Novel nuclear autoantigen with splicing factor motifs identified with antibody from hepatocellular carcinoma. 822 58

A Ubiquitin-like peptide was accidentally isolated from rat bladder by using 5% acetic acid wash while we were isolating antibacterial peptides. The purified molecule was obtained by reverse phase high performance liquid chromatography. Gas phase microsequence analysis indicated the N-terminal sequences of the molecule as follows: MET-GLN-ILE-PHE-VAL-LYS-THR-LEU-THR-GLY-LYS-THR-ILE-THR-LEU- GLU-VAL-GLU-PRO-SER-ASP-THR-ILE-GLU-ASN, which is homologous to human ubiquitin. Ubiquitin plays a role in the differentiation of pre-B lymphocytes, Thus, it is suggested from the findings of this molecule and the endogenous antibacterial polypeptides in mucosa or mucosal epithelium that mucosal epithelium also might be one of immune cells or immunity-associated cells, which may secrete effector molecules directly to kill adherent microbes and produce regulating factors in mucosal immune response.
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PMID:[Rat bladder ubiquitin-like molecule: isolation, purification and N-terminal sequencing]. 824 87

This paper concerns with the changes of plasma amino acid (AA) concentrations of N. 10 ELBW infants receiving a regimen of partial parenteral nutrition including human serum albumin (HSA) as a protein supply. The plasma AA concentration has been compared with VLBW infants orally fed with human milk (HM) or human milk supplemented with human milk protein (HMP). As for the essential AA: in comparison to VLBW infants fed HM, the plasma concentration of VAL, PHE and LYS is significantly higher, that of THR, MET, LEU and HIS is similar, whereas that of ILE is significantly lower; in comparison to VLBW infants fed HMP, with the exception of PHE whose plasma concentration is higher, concentration of essential AA significantly lower; the percentage ratio between plasma concentration and intake is in the range of 1,4 to 3,3, except for LYS (= 0.83), indicating a good efficacy of the i.v. administered HSA as AA source, or a slow plasma clearance or a sustained flux of AA from body protein catabolism. Further researches are needed to investigate these aspects and the intermediate steps between i.v. infusion of HSA and the utilization of the component AA for body protein synthesis.
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PMID:[The partial parenteral nutrition of preterm infants with a body weight < 1000 g: the effects of an infusion of human albumin on plasma amino acid concentration]. 825 73

In this report we present some of the biochemical properties of the enzyme, here called pp28(PTK), isolated from particulate fraction of rat spleen (1). The kinase is very susceptible for polyions as regulators of the enzymatic activity. The polyanions like dextran sulfate or heparin inhibited, and polycations such as spermidin, protamin, poly-L-lysine and some random polypeptides containing tyrosine besides a basic amino acid, stimulated the enzyme markedly. The kinase showed high sensitivity towards class IA salts. In the casein phosphorylation reaction the apparent Km value for ATP was 4 microM. An unusual property is associated with autophosphorylation which leads to a reduced activity towards external substrates. Some kinase inhibitors described in the literature were tested for their potency.
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PMID:Biochemical properties of a novel 28KDA protein tyrosine kinase partially purified from the particulate fraction of rat spleen. 826 1

The transmembrane PTPase HPTP beta differs from its related family members in having a single rather than a tandemly duplicated cytosolic catalytic domain. We have expressed the 354-amino acid, 41-kDa human PTP beta catalytic fragment in Escherichia coli, purified it, and assessed catalytic specificity with a series of pY peptides. HPTP beta shows distinctions from the related LAR PTPase and T cell CD45 PTPase domains: it recognizes phosphotyrosyl peptides of 9-11 residues from lck, src, and PLC gamma with Km values of 2, 4, and 1 microM, some 40-200-fold lower than the other two PTPases. With kcat values of 30-205 s-1, the catalytic efficiency, kcat/Km, of the HPTP beta 41-kDa catalytic domain is very high, up to 5.7 x 10(7) M-1 s-1. The peptides corresponding to PLC gamma (766-776) and EGFR (1,167-1,177) phosphorylation sites were used for structural variation to assess pY sequence context recognition by HPTP beta catalytic domain. While exchange of the alanine residue at the +2 position of the PLC gamma (Km of 1 microM) peptide to lysine or aspartic acid showed little or no effect on substrate affinity, replacement by arginine increased the Km 35-fold. Similarly, the high Km value of the EGFR pY peptide (Km of 104 microM) derives largely from the arginine residue at the +2 position of the peptide, since arginine to alanine single mutation at the -2 position of the EGFR peptide decreased the Km value 34-fold to 3 microM. Three thiophosphotyrosyl peptides have been prepared and act as substrates and competitive inhibitors of these PTPase catalytic domains.
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PMID:Substrate specificities of catalytic fragments of protein tyrosine phosphatases (HPTP beta, LAR, and CD45) toward phosphotyrosylpeptide substrates and thiophosphotyrosylated peptides as inhibitors. 831 1

Lysosomal cathepsin B but not L degraded rAPP751 to yield C-terminal 19-25 kDa fragments containing beta A4, reinforcing the view that acidic proteases participate in endosomal-lysosomal processing to yield amyloidogenic fragments in situ. This mechanism is consistent with fragmentation of endogenous APPs within clathrin-coated vesicles (CVs) by vesicular hydrolases, with the appearance of C-terminal amyloidogenic fragments following incubation at pH 6.5. A neutral endopeptidase resembling NEP 24.11 (PS-NEP) purified from detergent extracts of human brain degraded rAPP751; however, breakdown was not blocked robustly by metal chelators or phosphoramidon, suggesting the presence of an alternative processing enzyme. Effects of other inhibitors showed that breakdown was mediated by serine-protease-like component(s). A phosphoramidon-insensitive metalloendopeptidase (PI-NEP) partially purified from rat brain P2 using detergents, and resembling NEP 24.15, showed no activity towards rAPP751. Peptides containing putative beta- or gamma-secretase sites were synthesized for purposes of examining their metabolism by the brain enzymes. Those containing beta-secretase sites were hydrolysed at one or more sites by the four enzymes, but only PI- and PS-NEP acted at the Met-Asp site of Ac-Val-Lys-Met-Asp-Ala-Glu-Phe-Arg.NH2. In the case of substrates containing the gamma-site, these two categories of enzymes were the only ones degrading N-Ac-Ile-Ala.NH2. These data imply that the brain metalloendopeptidases, while inactive towards intact precursors, may be involved in turnover of intermediates containing beta- or gamma-sites.
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PMID:Brain cathepsin B but not metalloendopeptidases degrade rAPP751 with production of amyloidogenic fragments. Comparison with synthetic peptides emulating beta- and gamma-secretase sites. 853 84

Protamine sulfate is routinely administered after cardiopulmonary bypass to reverse systemic heparinization, but may cause a severe hypotensive reaction in as many as 2% of patients. Research Medical, Inc., has developed an extracorporeal venovenous heparin removal device (HRD) for use in patients at high risk for a protamine reaction. Circulation through the HRD removes heparin by hollow fiber plasma separation and selective sorption of anionically charged heparin to a polycationically charged poly-L-lysine ligand coupled to a agarose substrate. The heparin depleted plasma then reenters the whole blood pathway and is returned to the patient through the double lumen catheter in the right atrium. To evaluate the HRD in a clinically relevant model, cardiopulmonary bypass was performed in pigs using RA-Ao cardiopulmonary bypass (120 min) with systemic heparinization (300 IU/kg), a nonpulsatile pump with a membrane oxygenator, and systemic hypothermia (28 degrees C). Group 1 (HEP n = 7) had no intervention to neutralize the heparin; Group 2 (HRD n = 7) used the HRD. After 19.7 +/- 4.2 min of circulation through the HRD, the activated clotting time had returned to baseline, whereas the pigs in the HEP group were still anticoagulated (activated clotting time = 396 +/- 152 sec; time to baseline was 124 +/- 9 min). There were no significant differences between groups with respect to hemodynamics, hematocrit levels, leukocyte profiles, or platelet counts, HRD is an effective heparin removal device in a pig model of cardiopulmonary bypass and awaits a phase I clinical trial in humans.
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PMID:Reversal of anticoagulation without protamine using a heparin removal device after cardiopulmonary bypass. 855 77

Achondroplasia, the most common genetic form of dwarfism, is an autosomal dominant disorder whose underlying mechanism is a defect in the maturation of the cartilage growth plate of long bones. Achondroplasia has recently been shown to result from a Gly to Arg substitution in the transmembrane domain of the fibroblast growth factor receptor 3 (FGFR3), although the molecular consequences of this mutation have not been investigated. By substituting the transmembrane domain of the Neu receptor tyrosine kinase with the transmembrane domains of wild-type and mutant FGFR3, the Arg380 mutation in FGFR3 is shown to activate both the kinase and transforming activities of this chimeric receptor. Residues with side chains capable of participating in hydrogen bond formation, including Glu, Asp, and to a lesser extent, Gln, His and Lys, were able to substitute for the activating Arg380 mutation. The Arg380 point mutation also causes ligand-independent stimulation of the tyrosine kinase activity of FGFR3 itself, and greatly increased constitutive levels of phosphotyrosine on the receptor. These results suggest that the molecular basis of achondroplasia is unregulated signal transduction through FGFR3, which may result in inappropriate cartilage growth plate differentiation and thus abnormal long bone development. Achondroplasia may be one of the number of cogenital disorders where constitutive activation of a member of the FGFR family leads to development abnormalities.
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PMID:Constitutive activation of fibroblast growth factor receptor 3 by the transmembrane domain point mutation found in achondroplasia. 859 35


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