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

Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: beta-adrenergic receptor kinase (beta ARK), which phosphorylates the agonist-occupied receptor, and its functional cofactor, beta-arrestin. beta ARK is a member of a multigene family, consisting of six known subtypes, which have also been named G-protein-coupled receptor kinases (GRK 1 to 6) due to the apparently unique functional association of such kinases with this receptor family. The gene for beta ARK1 has been localized to human chromosome 11q13. The four members of the arrestin/beta-arrestin gene family identified so far are arrestin, X-arrestin, beta-arrestin 1, and beta-arrestin 2. Here we report the chromosome mapping of the human gene for beta-arrestin 1 (ARRB1) to chromosome 11q13 by fluorescence in situ hybridization (FISH). Two-color FISH confirmed that the two genes coding for the functionally related proteins beta ARK1 and beta-arrestin 1 both map to 11q13.
 ...
PMID:Assignment of the beta-arrestin 1 gene (ARRB1) to human chromosome 11q13. 789 72

Based on the established role of beta-adrenergic receptor kinase (beta ARK) and beta-arrestin in the desensitization of several G protein-coupled receptors, we investigated the effect of chronic morphine administration on beta ARK and beta-arrestin levels in selected brain areas. Levels of beta ARK were measured by blot immunolabeling analysis using antibodies specific for two known forms of beta ARK, i.e., beta ARK1 and beta ARK2. It was found that chronic morphine treatment produced an approximately 35% increase in levels of beta ARK1 immunoreactivity in the locus coeruleus, but not in several other brain regions studied. In contrast, chronic morphine treatment failed to alter levels of beta ARK2 immunoreactivity in any of the brain regions studied. Levels of beta-arrestin immunoreactivity, measured using an antiserum that recognizes two major forms of this protein in brain, were also found to increase (by approximately 20%) in the locus coeruleus. It is proposed that chronic morphine regulation of beta ARK1 and beta-arrestin levels may contribute to opioid-receptor tolerance that is known to occur in this brain region.
 ...
PMID:Chronic morphine administration increases beta-adrenergic receptor kinase (beta ARK) levels in the rat locus coeruleus. 793 57

Recent progress on the activation of G protein-coupled receptor kinases is reviewed. beta-Adrenergic receptor kinase (beta ARK) is activated by G protein beta gamma -subunits, which interact with the carboxyl terminal portion of beta ARK. Muscarinic receptor m2-subtypes are phosphorylated by beta ARK1 in the central part of the third intracellular loop (I3). Phosphorylation of I3-GST fusion protein by beta ARK1 is synergistically stimulated by the beta gamma -subunits and mastoparan or a peptide corresponding to portions adjacent to the transmembrane segments of m2-receptors or by beta gamma -subunits and the agonist-bound I3-deleted m2 variant. These results indicate that agonist-bound receptors serve as both substrates and activators of beta ARK.
 ...
PMID:[Regulation of G protein-coupled receptor kinase activity]. 795 13

The beta gamma subunits (G beta gamma) of heterotrimeric G proteins modulate the activity of several signal-transducing effector molecules including G protein-coupled receptor kinases. G beta gamma binds to the carboxyl terminus of the beta-adrenergic receptor kinase (beta ARK) and regulates its activity. To investigate the effect of such a G beta gamma-binding domain on heterologous G beta gamma interactions, various receptors that can stimulate phospholipase C and/or type II adenylate cyclase were coexpressed in COS-7 cells with the carboxyl terminus of beta ARK1. Phosphoinositol hydrolysis in response to activation of receptors that stimulate phospholipase C via Gi beta gamma (alpha 2-adrenergic and M2-muscarinic cholinergic receptors) was markedly inhibited by the coexpressed beta ARK1 polypeptide, whereas that mediated by Gq alpha subunits (alpha 1-adrenergic and M1-muscarinic cholinergic receptors) was unaffected. Increased cellular cAMP levels due to stimulation of receptors and coexpressed adenylate cyclase II displayed marked inhibition in the presence of the beta ARK1 polypeptide. Moreover, inhibition of adenylate cyclase produced by alpha 2-adrenergic receptor stimulation (a Gi alpha-mediated process) was unaffected, indicating that the beta ARK1 polypeptide provides a useful tool for distinguishing between G alpha and G beta gamma pathways.
 ...
PMID:Cellular expression of the carboxyl terminus of a G protein-coupled receptor kinase attenuates G beta gamma-mediated signaling. 811 63

Ligand-induced activation of many receptors leads to dissociation of the alpha- and beta gamma-subunit complexes of heterotrimeric G proteins, both of which regulate a variety of effector molecules involved in cellular signaling processes. In one case, a cytosolic enzyme, the beta-adrenergic receptor kinase (beta ARK) binds to the dissociated, prenylated, membrane-anchored beta gamma-subunits of heterotrimeric G proteins (G beta gamma) and is thereby targeted to its membrane-bound receptor substrate. Quite recently, numerous proteins involved in cellular signal transduction have been shown to contain sequences homologous with a "domain" originally identified in the protein "pleckstrin" (pleckstrin homology domain; PH domain) and subsequently found in the G beta gamma interaction region of the beta ARK sequence. Here we demonstrate that glutathione S-transferase-fusion proteins, containing sequences encompassing the PH domain of nine proteins from this group, bind G beta gamma to varying extents. Binding of G beta gamma to these fusion proteins was documented either by a direct binding assay or by ability to block G beta gamma-mediated membrane translocation of beta ARK1. G beta gamma binding to these fusion proteins was inhibited by the alpha subunit of Go (Go alpha), indicating that the binding of G beta gamma to G alpha and the PH domain-containing fusion proteins is mutually exclusive. Studies with a series of truncated PH domains derived from the Ras-guanine-nucleotide-releasing factor indicate that the G beta gamma binding domain includes only the C-terminal portion of the PH domain and sequences just distal to this. Protein-protein interactions between G beta gamma and PH domain-containing proteins may play a significant role in cellular signaling analogous to that previously demonstrated for Src homology 2 and 3 domains.
 ...
PMID:Binding of G protein beta gamma-subunits to pleckstrin homology domains. 814 1

The beta-adrenergic receptor kinase (beta ARK) phosphorylates its membrane-associated receptor substrates, such as the beta-adrenergic receptor, triggering events leading to receptor desensitization. beta ARK activity is markedly stimulated by the isoprenylated beta gamma subunit complex of heterotrimeric guanine nucleotide-binding proteins (G beta gamma), which translocates the kinase to the plasma membrane and thereby targets it to its receptor substrate. The amino-terminal two-thirds of beta ARK1 composes the receptor recognition and catalytic domains, while the carboxyl third contains the G beta gamma binding sequences, the targeting domain. We prepared this domain as a recombinant His6 fusion protein from Escherichia coli and found that it had both independent secondary structure and functional activity. We demonstrated the inhibitory properties of this domain against G beta gamma activation of type II adenylyl cyclase both in a reconstituted system utilizing Sf9 insect cell membranes and in a permeabilized 293 human embryonic kidney cell system. Gi alpha-mediated inhibition of adenylyl cyclase was not affected. These data suggest that this His6 fusion protein derived from the carboxyl terminus of beta ARK1 provides a specific probe for defining G beta gamma-mediated processes and for studying the structural features of a G beta gamma-binding domain.
 ...
PMID:Functionally active targeting domain of the beta-adrenergic receptor kinase: an inhibitor of G beta gamma-mediated stimulation of type II adenylyl cyclase. 817 Sep 60

We have mutated a single residue, Thr373 [corrected], in the C-terminal portion of the third intracellular loop of the alpha 2C10-adrenergic receptor into five different amino acids. In analogy with the effect of similar mutations in the alpha 1B- and beta 2-adrenergic receptors, these substitutions resulted in two major biochemical modifications: 1) increased constitutive activity of the alpha 2-adrenergic receptor leading to agonist-independent inhibition of adenylyl cyclase and 2) increased affinity of the receptor for binding agonist but not antagonists. The increased constitutive activity of the mutated alpha 2-adrenergic receptors could be inhibited by pertussis toxin, clearly indicating that it results from spontaneous ligand-independent receptor coupling to Gi. In contrast, the increased affinity of the mutant receptors for binding agonists was unaffected by pertussis toxin treatment, indicating that this is an inherent property of the receptors not dependent on interaction with Gi. Coexpression of the receptor mutants with the receptor-specific kinase, beta ARK1, indicated that the constitutively active alpha 2-adrenergic receptors are substrates for beta-adrenergic receptor kinase (beta ARK)-mediated phosphorylation even in the absence of agonist. These findings strengthen the idea that constitutively active adrenergic receptors mimic the "active" state of a G protein-coupled receptor adopting conformations similar to those induced by agonist when it binds to wild type receptors. In addition, these results extend the notion that in the adrenergic receptor family the C-terminal portion of the third intracellular loop plays a general role in the processes involved in receptor activation.
 ...
PMID:Constitutively active mutants of the alpha 2-adrenergic receptor. 839 65

Human neutrophils express several distinct guanine nucleotide binding (G)-protein-coupled receptors that mediate their responsiveness to chemoattractants. Phosphorylation by receptor-specific and second messenger-activated protein kinases is a common mechanism for regulation of G-protein-coupled receptors. To explore the possibility that chemoattractant receptors are regulated by unique receptor kinases, we utilized PCR to identify receptor kinases in human neutrophils. Here, we report the isolation of three G-protein-coupled-receptor-kinase (GPRK)-like sequences termed GPRK5, GPRK6, and GPRK7 in addition to the beta-adrenergic receptor kinase (beta ARK) 1 and 2 isoforms (beta ARK1 and beta ARK2). Two, GPRK5 and GPRK6, showed high homology at the amino acid level to the recently identified receptor-kinase-like sequence localized close to the Huntington disease locus. GPRK7 is of interest in that it contains a DLG (Asp-Leu-Gly) amino acid motif of receptor kinases preceded by a DFD (Asp-Phe-Asp) motif. We isolated cDNAs corresponding to GPRK6; the complete sequence shows > 66% identity and 81% similarity at the amino acid level to the GPRK from the Huntington disease locus. The GPRK6 cDNA probe hybridizes to two mRNAs of 2.9 and 2.1 kb that were expressed in all the tested human tissues including HL-60 cells and neutrophils. Genomic Southern blot analysis and chromosome mapping showed that GPRK6 hybridizes to two closely related genes located on chromosomes 5 and 13 and are, therefore, distinct from the GPRK located near the Huntington disease locus on chromosome 4. The identification herein of three putative receptor kinases indicates that in addition to beta ARK and rhodopsin kinase subfamilies, there are other receptor-kinase subfamilies that regulate the broad spectrum of G-protein-coupled receptors.
 ...
PMID:Identification of additional members of human G-protein-coupled receptor kinase multigene family. 841 12

Receptor phosphorylation is a key step in the process of rapid desensitization of the beta-adrenergic and other related G-coupled receptors. A specific kinase (called beta-adrenergic receptor kinase, beta ARK) has been identified, which phosphorylates the agonist-occupied form of these receptors. We have cloned the cDNA for human beta ARK1. The full-length cDNA was inserted in an expression vector (pBJI neo) and used for the transfection of eukaryotic cells (COS7). The kinase activity of the cytosolic fraction of COS7 cells was assayed 72 hours after beta ARK1 transfection. A 40-70 fold increase in cytosolic beta ARK1 activity was observed. To validate this approach we demonstrated a different degree of kinase inhibition by various types of heparin. Our system, based on transient gene expression and in vitro phosphorylation of rhodopsin, represents a new method to screen for pharmacological agents acting on this kinase.
 ...
PMID:Rhodopsin phosphorylation by transiently expressed human beta ARK1: a new method for drug development. 845 May 12

The beta gamma subunits of heterotrimeric G proteins play important roles in regulating receptor-stimulated signal transduction processes. Recently appreciated among these is their role in the signaling events that lead to the phosphorylation and subsequent desensitization of muscarinic cholinergic (Haga, K., and Haga, T. (1992) J. Biol. Chem. 267, 2222-2227) and beta-adrenergic (Pitcher, J. A., Inglese, J., Higgins, J. B., Arriza, J. L., Casey, P. J., Kim, C., Benovic, J. L., Kwatra, M. M., Caron, M. G., and Lefkowitz, R. J. (1992) Science 257, 1264-1267) receptors. Beta gamma mediates the membrane targeting of the beta-adrenergic receptor kinase (beta ARK), in response to receptor activation, through a specific beta ARK-beta gamma interaction. This process utilizes the membrane-anchoring properties of the isoprenylated gamma subunit of beta gamma. In the present study, we have employed three distinct approaches to identify the region within the carboxyl terminus of beta ARK which binds beta gamma and thereby results in membrane translocation. We studied the ability of beta gamma to enhance the enzymatic activity of a series of truncated mutants of bovine beta ARK1, the ability of glutathione S-transferase fusion proteins containing various lengths of the carboxyl terminus of beta ARK to bind beta gamma subunits, and the ability of synthetic peptides comprised of beta ARK sequences to inhibit beta gamma activation of beta ARK1. We find that the minimal beta gamma binding domain of beta ARK is localized to a 125-amino acid residue stretch, the distal end of which is located 19 residues from the carboxyl terminus. A single 28-mer peptide (Trp643 to Ser670) derived from this sequence effectively inhibited beta gamma activation of beta ARK1, with an IC50 of 76 microM. The identification of this "beta gamma binding domain" on beta ARK and the development of peptide inhibitors provide important tools for the study of G protein-coupled receptor desensitization, as well as for the investigation of beta gamma activation of other G protein-effector systems.
 ...
PMID:The binding site for the beta gamma subunits of heterotrimeric G proteins on the beta-adrenergic receptor kinase. 846 35


<< Previous 1 2 3 Next >>