title: An intact helical domain is required for Gα14 to stimulate phospholipase Cβ.
abstract: BACKGROUND
  Stimulation of phospholipase Cβ (PLCβ) by the activated α-subunit of Gq (Gαq) constitutes a major signaling pathway for cellular regulation, and structural studies have recently revealed the molecular interactions between PLCβ and Gαq. Yet, most of the PLCβ-interacting residues identified on Gαq are not unique to members of the Gαq family. Molecular modeling predicts that the core PLCβ-interacting residues located on the switch regions of Gαq are similarly positioned in Gαz which does not stimulate PLCβ. Using wild-type and constitutively active chimeras constructed between Gαz and Gα14, a member of the Gαq family, we examined if the PLCβ-interacting residues identified in Gαq are indeed essential.
  
  
  RESULTS
  Four chimeras with the core PLCβ-interacting residues composed of Gαz sequences were capable of binding PLCβ2 and stimulating the formation of inositol trisphosphate. Surprisingly, all chimeras with a Gαz N-terminal half failed to functionally associate with PLCβ2, despite the fact that many of them contained the core PLCβ-interacting residues from Gα14. Further analyses revealed that the non-PLCβ2 interacting chimeras were capable of interacting with other effector molecules such as adenylyl cyclase and tetratricopeptide repeat 1, indicating that they could adopt a GTP-bound active conformation.
  
  
  CONCLUSIONS
  Collectively, our study suggests that the previously identified PLCβ-interacting residues are insufficient to ensure productive interaction of Gα14 with PLCβ, while an intact N-terminal half of Gα14 is apparently required for PLCβ interaction.
authors.affiliation: Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. dawnakwan@gmail.com.
authors.forename: Dawna H T
authors.initials: DH
authors.lastname: Kwan
authors.affiliation: Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. kmwongaf@connect.ust.hk.
authors.forename: Ka M
authors.initials: KM
authors.lastname: Wong
authors.affiliation: Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. anthonyc@ust.hk.
authors.forename: Anthony S L
authors.initials: AS
authors.lastname: Chan
authors.affiliation: Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. bolisa@ust.hk.
authors.forename: Lisa Y
authors.initials: LY
authors.lastname: Yung
authors.affiliation: Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. boyung@ust.hk.|State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. boyung@ust.hk.
authors.forename: Yung H
authors.initials: YH
authors.lastname: Wong
mesh_terms: D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D054799:Phospholipase C beta / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D054799:Phospholipase C beta; C119109:GNA14 protein, human; D043802:GTP-Binding Protein alpha Subunits, Gq-G11