Phosphoprotein Phosphatase Activity in Normal and Dystonic Human Fibroblast Plasma Membranes

Abstract

Abstract

There is increasing evidence that the level of membrane protein phosphorylation may be related to the regulation of membrane function. We have characterized the phosphoprotein phosphatase activity in membranes prepared from normal human skin fibroblast cultures and from patients with dystonia musculorum deformans (DMD). Protein phosphatase activity was linear with time and membrane protein with a broad pH optimum between 6.0 and 7.5. Fluoride, molybdate, and compounds containing a pyrophosphate moiety were inhibitory. There was no significant difference in the K_m or V_max when fibroblast membranes from patients with DMD were compared to those from normal controls.