Abstract
Suspensions of cyclic[c]AMP sensitive cells of D. discoideum responded to a cAMP pulse with increased methylation of a protein of MW about 120,000 and increased phospholipid demethylation. Protein methylation reached its peak 15-30 s after cAMP addition. Phospholipid demethylation reached its maximum within 2 min and basal levels were recovered in 3 min. S-Adenosyl-L-methionine is probably the methyl donor. In vitro addition of 0.25 mM and 25 .mu.M S-adenosyl-L-methionine to sonicated D. discoideum cells inhibited ATP-dependent 45Ca2+ uptake by 70 and 25%, respectively. Based on this evidence it is proposed that protein and phospholipid methylation are involved in D. discoideum chemotaxis probably by regulation of intracellular Ca2+ movements.