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Abstract:
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The glutathione -conjugate transporter protein DNP -SG ATPase was demonstrated to be identical to the independently cloned Ral -effector , Ralbp1 . Glutathione -conjugate transport is linked to substrate -stimulated ATPase activity , while GTPase stimulating activity (GAP -activity ) , and clathrin -coated pit -binding activity was demonstrated for this protein by different groups of investigators . The relationship between these activities and physiological functions of Ralbp1 were not clear . The present studies were designed to address the hypothesis that the ability of Ralbp1 to couple the hydrolysis of ATP with the movement of substances , i .e . its transport activity , is the crucial element that allows Ralbp1 to function as a stress -defense protein . Results of these studies , demonstrating 1 ) the requirement of Ralbp1 for PKC alpha mediated resistance -signaling , 2 ) the identification of transmembrane spanning domains of Ralbp1 and requirement of membrane anchorage for transport function , and 3 ) the requirement of transport function for clathrin -dependent ligand -receptor endocytosis to occur , offer strong evidence in support of this proposal . |