Photoaffinity labeling of protein phosphatase 2A, the receptor for a tumor promoter okadaic acid, by [27-3H]methyl 7-O-(4-azidobenzoyl)okadaate.
The interaction of okadaic acid and a protein phosphatase, which is the receptor for a tumor promoter, okadaic acid, was studied. [27-3H]Methyl 7-O-(4-azidobenzoyl)okadaate was synthesized and protein phosphatase 2A, which consists of two regulatory subunits of 65 kDa and 42 kDa and a catalytic subunit of 37 kDa, was purified from bovine brain. After UV irradiation of the reaction mixture, [3H]methyl 7-O-(4-azidobenzoyl)okadaate covalently bound to the catalytic subunit, but not to the two regulatory subunits. These results strongly suggest that okadaic acid, a potent inhibitor of protein phosphatases, binds specifically to the catalytic subunit rather than to the other regulatory subunits.
Nishiwaki
S
S
Cancer Prevention Division, National Cancer Center Research Institute, Tokyo, Japan.
Fujiki
H
H
Suganuma
M
M
Ojika
M
M
Yamada
K
K
Sugimura
T
T
D000345:Affinity Labels; D000818:Animals; D001386:Azides / Q000494:pharmacology* / Q000528:radiation effects; D002273:Carcinogens / Q000378:metabolism*; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D004988:Ethers, Cyclic / Q000378:metabolism* / Q000494:pharmacology* / Q000528:radiation effects; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D054648:Protein Phosphatase 2; D011955:Receptors, Drug / Q000378:metabolism; D014466:Ultraviolet Rays
D000345:Affinity Labels; D001386:Azides; D002273:Carcinogens; D004988:Ethers, Cyclic; D011955:Receptors, Drug; C065489:27-methyl 7-O-(4-azidobenzoyl)okadaate; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2