title: The pleckstrin homology domain of phospholipase C-beta2 as an effector site for Rac.
abstract: Increasing evidence links the activation of Rho family GTPases to the stimulation of lipid hydrolysis catalyzed by phospholipase C (PLC)-beta isozymes. To better define this relationship, members of a library of recombinant Rho GTPases were screened for their capacity to directly engage various purified PLC-beta isozymes. Of the 17 tested members of the Rho family, only the active isoforms of Rac (Rac1, Rac2, and Rac3) both stimulate PLC-beta activity in vivo and bind PLC-beta2 and PLC-beta3, but not PLC-beta1, in vitro. Furthermore, the recognition site for Rac GTPases was localized to the pleckstrin homology (PH) domain of PLC-beta2, and this PH domain is fully sufficient to selectively interact with the active versions of the Rac GTPases, but not with other similar Rho GTPases. Together, these findings present a quantitative evaluation of the direct interactions between Rac GTPases and PLC-beta isozymes and define a novel role for the PH domain of PLC-beta2 as a putative effector site for Rac GTPases.
authors.affiliation: Department of Pharmacology, The University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Snyder
authors.forename: Alex U
authors.initials: AU
authors.lastname: Singer
authors.forename: Michele R
authors.initials: MR
authors.lastname: Wing
authors.forename: T Kendall
authors.initials: TK
authors.lastname: Harden
authors.forename: John
authors.initials: J
authors.lastname: Sondek
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D001798:Blood Proteins / Q000235:genetics*; D019556:COS Cells; D018076:DNA, Complementary; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D054799:Phospholipase C beta; D010750:Phosphoproteins / Q000235:genetics*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D010738:Type C Phospholipases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D000097766:RAC2 GTP-Binding Protein
chemical_list: D001798:Blood Proteins; D018076:DNA, Complementary; D007527:Isoenzymes; D054799:Phospholipase C beta; D010750:Phosphoproteins; D010738:Type C Phospholipases; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C411563:RAC3 protein, human; C039077:platelet protein P47; C518033:PLCB1 protein, human; C518036:PLCB2 protein, human; C518039:PLCB3 protein, human