Calcium and calmodulin stimulated in vitro phosphorylation of rooster brain tubulin and MAP-2 following a single oral dose of tri-o-cresyl phosphate.

The effect of a single oral administration of 750 mg/kg tri-o-cresyl phosphate (TOCP) on endogenous phosphorylation of specific brain cytosolic proteins has been studied in roosters following the development of delayed neurotoxicity. In vitro phosphorylation assay using [gamma-32P]ATP was carried out. Proteins were then resolved on one dimensional 8% SDS-PAGE and two-dimensional gel electrophoresis, stained with Coomassie blue and autoradiographed. The amount of proteins, as well as the amount of 32P incorporation, were quantified by microdensitometry, TOCP-administration enhanced the phosphorylation of cytosolic proteins of M, 52-59 kDa, 70 kDa, and 300 kDa by as much as 155%, 199% and 166%, respectively. Two-dimensional gel electrophoresis confirmed the 52-59 kDa proteins as alpha and beta tubulin and the 300 kDa protein as microtubule-associated protein-2.