Interaction of p130 with, and consequent inhibition of, the catalytic subunit of protein phosphatase 1alpha.
The protein p130 was originally isolated from rat brain as an inositol 1,4,5-trisphosphate-binding protein with a domain organization similar to that of phospholipase C-delta1 but which lacks phospholipase C activity. Yeast two-hybrid screening of a human brain cDNA library for clones that encode proteins that interact with p130 has now led to the identification of the catalytic subunit of protein phosphatase 1alpha (PP1calpha) as a p130-binding protein. The association between p130 and PP1calpha was also confirmed in vitro by an overlay assay, a "pull-down" assay, and surface plasmon resonance analysis. The interaction of p130 with PP1calpha resulted in inhibition of the catalytic activity of the latter in a p130 concentration-dependent manner. Immunoprecipitation and immunoblot analysis of COS-1 cells that stably express p130 and of mouse brain extract with antibodies to p130 and to PP1calpha also detected the presence of a complex of p130 and PP1calpha. The activity of glycogen phosphorylase, which is negatively regulated by dephosphorylation by PP1calpha, was higher in COS-1 cells that stably express p130 than in control COS-1 cells. These results suggest that, in addition to its role in inositol 1,4,5-trisphosphate and Ca(2+) signaling, p130 might also contribute to regulation of protein dephosphorylation through its interaction with PP1calpha.
Yoshimura
K
K
Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
Takeuchi
H
H
Sato
O
O
Hidaka
K
K
Doira
N
N
Terunuma
M
M
Harada
K
K
Ogawa
Y
Y
Ito
Y
Y
Kanematsu
T
T
Hirata
M
M
D002384:Catalysis; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D054803:Phospholipase C delta; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010957:Plasmids; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D010738:Type C Phospholipases / Q000378:metabolism*
D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D010749:Phosphoprotein Phosphatases; D010738:Type C Phospholipases; C518024:PLCD1 protein, human; D054803:Phospholipase C delta; C518025:Plcd1 protein, mouse; C518026:Plcd1 protein, rat