[Phosphorylation of cytoplasmic proteins related to the multihormonal regulation of anterior pituitary cells].

Thyrotropin releasing hormone (TRH) stimulates the synthesis and release of prolactin in mammotropic cells of the anterior pituitary and in GH4C1 cells. TRH simultaneously enhances the phosphorylation of a small number of proteins revealed in GH4C1 cells by two dimensional gel electrophoresis. The same phosphoproteins could be detected in normal rat pituitary cells in primary culture and were phosphorylated with the same pharmacology as in GH4C1 cells. Moreover, these proteins may also be related to hormonal regulations of the other cell types of the anterior pituitary.