Dr. Browning will study hormone and second messenger-stimulated phosphorylation of the astrocytic cytoskeletal intermediate diameter filament proteins vimentin and glial fibrillary acidic protein (GFAP). Past studies identified neurohormone and cyclic AMP-stimulated multiple phosphorylations of these two proteins in intact cultured astrocytes. Recent studies have initiated the localization of the phosphorylation sites within the primary structure of the two proteins. The proposed research will further define these sites and test if manipulation of other regulatory parameters of the cultured astrocytes which change the phosphorylation of these proteins do so by phosphorylation of the same or different sites within the proteins. The protein kinase and protein phosphatase activities that are responsible for these phosphorylations will be identified. Affinity purified antibodies will be prepared against the phosphorylation sites and these antibodies will be used to localize the phosphorylation sites within the astrocytes with reference to gross cellular structure and other structural elements.
