Browsing by Author "Raj Shankar"
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PublicationArticle Developmental regulation and effect of early undernutrition on phosphorylation of rat cortical synaptic membrane proteins(1999) Tryambak Deo Singh; Raj ShankarUndernutrition during early postnatal life was employed in rats by restricting the feeding time. The synaptic membrane fraction from cerebral cortex of normal and undernourished rats of various ages was prepared and endogenous protein phosphorylation studied. Many of the synaptic membrane proteins were found to be phosphorylated in an age-dependent manner. Early undernutrition affects the phosphorylation of various proteins in a complex way; most affected were 48-, 52-, 61- and 74-kDa proteins. These proteins were found to have phosphorylations mainly at tyrosine residues. This finding indicates that tyrosine phosphorylations may be affected most by early undernutrition. Adequate nutrition after early undernutrition removes most of the effects of undernutrition on synaptic protein phosphorylation. To address the question of how undernutrition may affect protein phosphorylation, we studied the lipid content of synaptic membrane fraction as it can affect membrane properties, including the fluidity. We found that undernutrition affects phosphorylation of most of the synaptic membrane proteins in the same manner in which it affects the cholesterol-phospholipid ratio of synaptic membrane and, hence, the fluidity of the membrane. This indicates that lipid biosynthesis is one of the ways by which undernutrition can affect synaptic membrane protein phosphorylation. Copyright (C) 1999 ISDN.PublicationArticle Lithium regulation of protein phosphorylation in rat cerebral cortex slices in vitro(Taylor and Francis Inc., 1998) Tryambak Deo Singh; Raj ShankarThe aim of the present study was to evaluate the direct effect of Li+ find Na+-Li+ exchange on protein phosphorylation in rat cerebral cortex slices incubated in Krebs Ringer medium. When Na+ concentration was varied in the incubation medium, either by replacement with Li+ or sucrose, a variable effect on [(32P)] phosphate incorporation into proteins was observed. Protein phosphorylation in cerebral cortex slices was very low in the absence of Na+, and some dependence of phosphorylating system of neural tissue on extra cellular concentration of Na+ was evident. Lithium was not able to replace sodium as far as protein phosphorylation in cortical slices is concerned. Ouabain was more effective in a Li+ containing medium in inhibiting protein phosphorylation, presumably due to improper functioning of the sodium pump.PublicationArticle Reserpine inhibition of lipid peroxidation and protein phosphorylation in rat brain(1986) Sasanka Chakrabarti; Sajal Kumar; Raj Shankar[No abstract available]