Increased Phosphorylation of Specific Rat Cardiac and Retinal Proteins in Taurine-Depleted Animals: Isolation and Identification of the Phosphoproteins
Partial depletion of the tissue levels of taurine in the alive animal stimulates in vitro phosphorylation of both an ~20 kDa (94%) and an ~44 kDa (85%) protein present in subcellular fractions of the rat retina and heart. Tissue levels of taurine were reduced by feeding the animals 1.5% guanidinoethanesulfonic acid (GES) in their drinking water for 6 weeks. The increase in the in vitro phosphorylation of both the ~20 kDa and ~44 kDa proteins was reversed when the animals were subsequently given 1.5% taurine in their drinking water for an additional 6 weeks. Isolation, purification, tryptic digestion, and peptide sequence analysis of the retinal ~20 kDa phosphoprotein suggest that it is histone H2B. However, the results are ambiguous due to an impurity (<25%) in the retinal preparation. Sequence analysis of the ~44 kDa phosphoprotein indicates that it is pyruvate dehydrogenase.
KeywordsPyruvate Dehydrogenase Mitochondrial Fraction Approximate Molecular Weight Taurine Level Taurine Content
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