Taurine depletion in the intact animal stimulates in vitro phosphorylation of an approximately 44-kDa protein present in the mitochondrial fraction of the rat heart.

Sprague-Dawley rats were treated with 1.5% guanidinoethanesulfonic (GES) acid in their water in order to deplete the taurine levels partially in cardiac tissue. After 6 weeks of GES treatment, in vitro phosphorylation of a approximately 44 kDa protein present in the mitochondrial fraction of the rat heart was increased by 85%. The increase in the in vitro phosphorylation of the specific approximately 44 kDa protein after GES treatment was reversed when the animals were subsequently given 1.5% taurine in their drinking water for an additional 6 weeks. Taurine (1.5%) alone for a period of 6 weeks had no effect on the phosphorylation of the approximately 44 kDa protein. These results suggest that taurine has a regulatory role in the phosphorylation of a specific protein in cardiac tissue.