Effects of taurine on the phosphorylation of specific proteins in subcellular fractions of the rat retina.

The effects of 20 mM taurine on the phosphorylation of specific proteins in mitochondrial and rod outer segment subcellular fractions of the rat retina were measured. A band of protein with an apparent molecular weight of approximately 20K was consistently inhibited by taurine. Densitometry measurements performed on gel electrophoresis autoradiograms from the mitochondrial fraction demonstrated a 42.7 +/- 8.3% decrease due to taurine (20 mM) in the area corresponding to radioactivity from the approximately 20K phosphoprotein. However, only a 21.2 +/- 9.0% decrease was observed due to taurine in the rod outer segment preparation. These data suggest that taurine is exerting its primary effect on the phosphorylation of the approximately 20K molecular weight protein in the mitochondria of the retina. In addition, calmodulin and phorbol ester had no effect on the phosphorylation of the approximately 20K molecular weight protein.