Protein phosphatases 1 and 2A in rabbit ciliary epithelium and iris-ciliary body.
A significant dephosphorylation of exogenous phosphorylase a by serine/threonine protein phosphatases in tissue extracts of rabbit ciliary epithelium and iris-ciliary body was observed. Okadaic acid caused a concentration-dependent inhibition of this dephosphorylation. In a series of diluted samples, selective inhibitions of protein phosphatase 2A by 1 nM okadaic acid and protein phosphatase 1 by 1 microM okadaic acid were determined. In the preparation of ciliary epithelium, the ratio of protein phosphatase 1 to protein phosphatase 2A activity was estimated to be 1:2. Dephosphorylation by other phosphatases was little. In the preparation of iris-ciliary body, the ratio of protein phosphatase 1 to protein phosphatase 2A activity was approximately 2.5:1. Other phosphatases were also present.
Liu
J H
JH
Department of Ophthalmology, University of California, San Diego, La Jolla 92093-0946, USA.
D000818:Animals; D002924:Ciliary Body / Q000201:enzymology*; D004848:Epithelium / Q000201:enzymology; D004988:Ethers, Cyclic / Q000494:pharmacology; D007498:Iris / Q000201:enzymology*; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases / Q000032:analysis* / Q000037:antagonists & inhibitors; D010766:Phosphorylation / Q000187:drug effects; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D011817:Rabbits
D004988:Ethers, Cyclic; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2