EFFECT OF PHORBOL 12-MYRISTATE 13-ACETATE (PMA) ON THE PHOSPHOINOSITOL (PI) SYSTEM IN TETRAHYMENA - STUDY OF THE P-32 INCORPORATION AND BREAKDOWN OF PHOSPHOLIPIDS

Phorbol 12-myristate 13-acetate (PMA) treatment elicited an increased P-32 incorporation into phospholipids namely phosphatadyl-inositol (PI); phosphatidyl-inositol-4-phosphate (PIP); phosphatidyl-inositol-4,5-bis-phosphate (PIP2); phosphatidyl-acid (PA); phosphatidyl-choline (PC) and phosphatidyl-ethanolamine (PE) particularly at the 20-30th min after treatment. The ratio of members of the phosphoinositol system, especially PIP and PI, related to the total phospholipid content was increased. PMA (2 x 10(-7) M) was the most effective of the three concentrations tested. The results call attention to the presence of a working phosphoinositol system in Protozoa.