title: Interactions of G(h)/transglutaminase with phospholipase Cdelta1 and with GTP.
abstract: The inositol phosphate hydrolyzing activity of human phospholipase Cdelta1 (PLCdelta1) is markedly inhibited when the enzyme is coexpressed with the human heart G(h)/transglutaminase (TG) in human embryonic kidney cells. Because the cotransfection does not affect the amount of PLCdelta1 in the cells, the depression of phospholipase activity probably is a result of a direct interaction between the two proteins. An ELISA procedure was employed to document the associations of purified TG preparations from a variety of tissues (human red cells, rabbit lens, guinea pig liver) with PLCdelta1. Nucleotides (GTP > GDP > ATP > GMP = ADP, in order of decreasing efficiency) interfered with the formation of the PLCdelta1:TG complex. A conformational change in the TG partner, occurring with nucleotide binding, is thought to be responsible for dissociating the two proteins. The structural rearrangement produces a remarkable shift in the anodic mobility of TG in electrophoresis: TG(slow) + GTP -->/<-- [TG:GTP](fast). Altogether, our findings indicate that GTP controls PLCdelta1 activity by releasing this protein from an inhibitory association with G(h)/transglutaminase.
authors.affiliation: Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611-3008, USA.
authors.forename: S N
authors.initials: SN
authors.lastname: Murthy
authors.forename: J W
authors.initials: JW
authors.lastname: Lomasney
authors.forename: E C
authors.initials: EC
authors.lastname: Mak
authors.forename: L
authors.initials: L
authors.lastname: Lorand
mesh_terms: D000818:Animals; D002645:Chickens; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000201:enzymology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D007908:Lens, Crystalline / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D051379:Mice; D008954:Models, Biological; D010504:Periodic Acid; D054803:Phospholipase C delta; D011817:Rabbits; D011503:Transglutaminases / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D010504:Periodic Acid; D006160:Guanosine Triphosphate; D011503:Transglutaminases; D010738:Type C Phospholipases; C518024:PLCD1 protein, human; D054803:Phospholipase C delta; C518025:Plcd1 protein, mouse; D019204:GTP-Binding Proteins