Effects of choline and ethanolamine on the synthesis and breakdown of the inositol phospholipid (PI) system in Tetrahymena.

Lower concentrations of choline chloride and ethanolamine (10(-3) M; 10(-5) M) increased phosphatidyl inositol (PI), phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bisphosphate (PIP2) level of Tetrahymena, while higher concentrations (10(-2) M) decreased them. These two substances also influenced, however in a less obvious way, the transformation of inositol phospholipids. The experiments draw attention to the sensitivity of the precursors of the second messenger system at a phylogenetically low level.