title: Rho GTPase control of protein kinase C-related protein kinase activation by 3-phosphoinositide-dependent protein kinase.
abstract: The protein kinase C-related protein kinases (PRKs) have been shown to be under the control of the Rho GTPases and influenced by autophosphorylation. In analyzing the relationship between these inputs, it is shown that activation in vitro and in vivo involves the activation loop phosphorylation of PRK1/2 by 3-phosphoinositide-dependent protein kinase-1 (PDK1). Rho overexpression in cultured cells is shown to increase the activation loop phosphorylation of endogenous PRKs and is demonstrated to influence this process by controlling the ability of PRKs to bind to PDK1. The interaction of PRK1/2 with PDK1 is shown to be dependent upon Rho. Direct demonstration of ternary (Rho.PRK.PDK1) complex formation in situ is provided by the observation that PDK1 is recruited to RhoB-containing endosomes only if PRK is coexpressed. Furthermore, this in vivo complex is maintained after phosphoinositide 3-kinase inhibition. The control of PRKs by PDK1 thus evidences a novel strategy of substrate-directed control involving GTPases.
authors.affiliation: Imperial Cancer Research Fund, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Flynn
authors.forename: H
authors.initials: H
authors.lastname: Mellor
authors.forename: A
authors.initials: A
authors.lastname: Casamassima
authors.forename: P J
authors.initials: PJ
authors.lastname: Parker
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D016475:3T3 Cells; D000818:Animals; D002384:Catalysis; D004789:Enzyme Activation; D051379:Mice; D010766:Phosphorylation; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism* / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000502:physiology*
chemical_list: C061570:protein kinase N; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578564:Pdpk1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020741:rho GTP-Binding Proteins