The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Christine A Cartwright - One of the best experts on this subject based on the ideXlab platform.
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RACK1: a novel substrate for the Src protein-tyrosine kinase
Oncogene, 2002Co-Authors: Betty Y Chang, Rachel A Harte, Christine A CartwrightAbstract:RACK1 is one of a group of PKC-interacting proteins collectively called RACKs ( R eceptors for A ctivated C - K inases). Previously, we showed that RACK1 also interacts with the Src tyrosine kinase, and is an inhibitor of Src activity and cell growth. PKC activation induces the intracellular movement and co-localization of RACK1 and Src, and the tyrosine phosphorylation of RACK1. To determine whether RACK1 is a Src substrate, we assessed phosphorylation of RACK1 by various tyrosine kinases in vitro , and by kinase-active and inactive mutants of Src in vivo . We found that RACK1 is a Src substrate. Moreover, Src activity is necessary for both the tyrosine phosphorylation of RACK1 and the binding of RACK1 to Src's SH2 domain that occur following PKC activation. To identify the tyrosine(s) on RACK1 that is phosphorylated by Src, we generated and tested a series of RACK1 mutants. We found that Src phosphorylates RACK1 on Tyr 228 and/or Tyr 246, highly-conserved tyrosines located in the sixth WD repeat that interact with Src's SH2 domain. We think that RACK1 is an important Src substrate that signals downstream of growth factor receptor tyrosine kinases and is involved in the regulation of Src function and cell growth.
Yvon Jaillais - One of the best experts on this subject based on the ideXlab platform.
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tyrosine phosphorylation controls brassinosteroid receptor activation by triggering membrane release of its kinase inhibitor
Genes & Development, 2011Co-Authors: Yvon Jaillais, Michael Hothorn, Youssef Belkhadir, Tsegaye Dabi, Zachary L Nimchuk, Elliot M Meyerowitz, Joanne ChoryAbstract:Receptor tyrosine kinases control many critical processes in metazoans, but these enzymes appear to be absent in plants. Recently, two Arabidopsis receptor kinases—BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE1 (BAK1), the receptor and coreceptor for brassinosteroids—were shown to autophosphorylate on tyrosines. However, the cellular roles for tyrosine phosphorylation in plants remain poorly understood. Here, we report that the BRI1 KINASE INHIBITOR 1 (BKI1) is tyrosine phosphorylated in response to brassinosteroid perception. Phosphorylation occurs within a reiterated [KR][KR] membrane targeting motif, releasing BKI1 into the cytosol and enabling formation of an active signaling complex. Our work reveals that tyrosine phosphorylation is a conserved mechanism controlling protein localization in all higher organisms.
Betty Y Chang - One of the best experts on this subject based on the ideXlab platform.
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RACK1: a novel substrate for the Src protein-tyrosine kinase
Oncogene, 2002Co-Authors: Betty Y Chang, Rachel A Harte, Christine A CartwrightAbstract:RACK1 is one of a group of PKC-interacting proteins collectively called RACKs ( R eceptors for A ctivated C - K inases). Previously, we showed that RACK1 also interacts with the Src tyrosine kinase, and is an inhibitor of Src activity and cell growth. PKC activation induces the intracellular movement and co-localization of RACK1 and Src, and the tyrosine phosphorylation of RACK1. To determine whether RACK1 is a Src substrate, we assessed phosphorylation of RACK1 by various tyrosine kinases in vitro , and by kinase-active and inactive mutants of Src in vivo . We found that RACK1 is a Src substrate. Moreover, Src activity is necessary for both the tyrosine phosphorylation of RACK1 and the binding of RACK1 to Src's SH2 domain that occur following PKC activation. To identify the tyrosine(s) on RACK1 that is phosphorylated by Src, we generated and tested a series of RACK1 mutants. We found that Src phosphorylates RACK1 on Tyr 228 and/or Tyr 246, highly-conserved tyrosines located in the sixth WD repeat that interact with Src's SH2 domain. We think that RACK1 is an important Src substrate that signals downstream of growth factor receptor tyrosine kinases and is involved in the regulation of Src function and cell growth.
Robert L. Patrick - One of the best experts on this subject based on the ideXlab platform.
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Activation of striatal tyrosine hydroxylase by in vivo electrical stimulation: Comparison with cyclic AMP-mediated activation
Neurochemical Research, 1990Co-Authors: Tina L. Thompson, Kathryn A. Colby, Robert L. PatrickAbstract:These studies were carried out to characterize the activation of rat striatal tyroxine hydroxylase produced by depolarization of the medial forebrain bundle and to evaluate the possible role of cyclic AMP as a mediator of this activation. The enzymatic properties of tyrosine hydroxylase following in vivo depolarization were compared to those produced by treatment of striatal synaptosomes with dibutyryl cyclic AMP (dbcAMP). Similar effects were observed with regard to enzyme distribution, altered sensitivity to dopamine-induced inhibition, and activity as a function of tyrosine concentration. However, differences between the two treatments were also apparent. First, treatment with dbcAMP shifted the pH optimum from 6.2 to 7.0. In contrast, electrical stimulation decreased the rate of decline in activity as the pH was increased above the optimum, but did not shift the pH optimum. Second, plots of tyrosine hydroxylase activity versus cofactor concentration revealed two enzyme forms for both control and electrically stimulated preparations. However, dbcAMP treatment converted the enzyme to a single high affinity form. These results can be explained by one of the following: (1) cyclic AMP is the sole mediator of enzyme activation, but does not produce a maximally activated enzyme following in vivo depolarization (2) cyclic AMP is only one of several mediators involved or (3) cyclic AMP is not involved in depolarization-induced activation, with activation occurring via the mediation of other intracellular messengers, such as calcium.
Joanne Chory - One of the best experts on this subject based on the ideXlab platform.
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tyrosine phosphorylation controls brassinosteroid receptor activation by triggering membrane release of its kinase inhibitor
Genes & Development, 2011Co-Authors: Yvon Jaillais, Michael Hothorn, Youssef Belkhadir, Tsegaye Dabi, Zachary L Nimchuk, Elliot M Meyerowitz, Joanne ChoryAbstract:Receptor tyrosine kinases control many critical processes in metazoans, but these enzymes appear to be absent in plants. Recently, two Arabidopsis receptor kinases—BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE1 (BAK1), the receptor and coreceptor for brassinosteroids—were shown to autophosphorylate on tyrosines. However, the cellular roles for tyrosine phosphorylation in plants remain poorly understood. Here, we report that the BRI1 KINASE INHIBITOR 1 (BKI1) is tyrosine phosphorylated in response to brassinosteroid perception. Phosphorylation occurs within a reiterated [KR][KR] membrane targeting motif, releasing BKI1 into the cytosol and enabling formation of an active signaling complex. Our work reveals that tyrosine phosphorylation is a conserved mechanism controlling protein localization in all higher organisms.
