Regulation of guanylate and adenylate cyclase activities by lysolecithin.

Abstract

The guanylate cyclase activity [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] in membrane preparations from 3T3 mouse fibroblasts is stimulated approximately 5-fold by lysolecithin at concentrations of 100 .mu.g/ml and above. The stimulation of the adenylate cyclase activity in these preparations by sodium fluoride is inhibited up to 95% by lysolecithin over a similar concentration range. The regulatory properties of lysolecithin appear to result from the surfactant properties of the phospholipid, since the activity cannot be attributed to any single substructure within the molecule and lysolecithin affects the subcellular distribution of guanylate cyclase in rat heart homogenates in a manner similar to that reported for the non-ionic detergent Triton X-100. Stimulation of guanylate cyclase by lysolecithin was observed with membrane preparations from both 3T3 cells and simian virus 40 transformed 3T3 cells (SV3T3). A possible role for lysolecithin in the coordinate regulation of the intracellular levels of both cyclic nucleotides and in the control of the responsiveness of target tissues to hormone or mitogen stimulation is suggested.