Mechanism of assembly of G protein betagamma subunits by protein kinase CK2-phosphorylated phosducin-like protein and the cytosolic chaperonin complex.
Phosducin-like protein (PhLP) is a widely expressed binding partner of the G protein betagamma subunit complex (Gbetagamma) that has been recently shown to catalyze the formation of the Gbetagamma dimer from its nascent polypeptides. Phosphorylation of PhLP at one or more of three consecutive serines (Ser-18, Ser-19, and Ser-20) is necessary for Gbetagamma dimer formation and is believed to be mediated by the protein kinase CK2. Moreover, several lines of evidence suggest that the cytosolic chaperonin complex (CCT) may work in concert with PhLP in the Gbetagamma-assembly process. The results reported here delineate a mechanism for Gbetagamma assembly in which a stable ternary complex is formed between PhLP, the nascent Gbeta subunit, and CCT that does not include Ggamma. PhLP phosphorylation permits the release of a PhLP x Gbeta intermediate from CCT, allowing Ggamma to associate with Gbeta in this intermediate complex. Subsequent interaction of Gbetagamma with membranes releases PhLP for another round of assembly.
Lukov
Georgi L
GL
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Baker
Christine M
CM
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Ludtke
Paul J
PJ
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Hu
Ting
T
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Carter
Michael D
MD
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Hackett
Ryan A
RA
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Thulin
Craig D
CD
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
Willardson
Barry M
BM
Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602. Electronic address: barry_willardson@byu.edu.
D002352:Carrier Proteins / Q000502:physiology*; D047390:Casein Kinase II / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D018833:Chaperonins / Q000502:physiology*; D003600:Cytosol; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000096:biosynthesis*; D006801:Humans; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010766:Phosphorylation
D002352:Carrier Proteins; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; C098789:PDCL protein, human; D047390:Casein Kinase II; D018833:Chaperonins; D019204:GTP-Binding Proteins