A newly identified 50 kDa protein, which is associated with phosphodiesterase 3B, is phosphorylated by insulin in rat adipocytes.
Phosphodiesterase 3B (PDE3B), a major PDE isoform in adipocytes, plays a pivotal role in the anti-lipolytic action of insulin. Insulin phosphorylates and activates PDE3B in a phosphatidylinositol 3-kinase-dependent manner. We identified a new 50 kDa protein that is phosphorylated by insulin and is co-immunoprecipitated with PDE3B by anti-PDE3B antibodies in rat adipocytes. The insulin-induced phosphorylation of the 50 kDa protein was also detected in a cell free system against the N-terminal and the catalytic regions, which are more than 700 amino acids apart recognize the 50 kDa protein, suggesting that it is not a proteolytic product, but an associated protein with PDE3B. Phosphoamino acid analysis indicated that both serine and threonine residues in the 50 kDa protein were phosphorylated, but only serine residues in PDE3B were phosphorylated. Therefore, it appears likely that this is a new protein which is associated with PDE3B.
Onuma
Hiroshi
H
Department of Laboratory Medicine, Ehime University School of Medicine, Toon-shi, Ehime 791-0295, Japan. onuma@m.ehime-u.ac.jp
Osawa
Haruhiko
H
Ogura
Takahiro
T
Tanabe
Fumiko
F
Nishida
Wataru
W
Makino
Hideichi
H
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000737:chemistry* / Q000378:metabolism*; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D004305:Dose-Response Relationship, Drug; D007328:Insulin / Q000008:administration & dosage*; D008970:Molecular Weight; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology
D007328:Insulin; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517294:Pde3b protein, rat