Phosphatidylinositol‐specific phospholipase C solubilized G 2 acetylcholinesterase from plasma membranes of chromaffin cells

Using whole homogenates and defined subcellular fractions of bovine adrenal medulla, we investigated the properties of the dimeric G 2 molecular form of acetylcholinesterase (AChE), its distribution, and the mode of attachment to chromaffin cells. Our studies indicate that a substantial fraction of the G 2 form is specifically susceptible to solubilization by phosphatidylinositol‐specific phospholipase C (PIPLC) from subcellular fractions enriched with plasma membrane fragments. The results suggest that the G 2 form of AChE is anchored in the plasma membrane to a glycolipid domain that contains phosphatidylinositol. Since a Ca +2 ‐dependent PIPLC has been previously described in chromaffin granules, it is possible that the adrenal AChE could be released by a system reminiscent of that involved in the case of the surface glycoprotein of Trypanosoma brucei .