Phosphatidylinositol-specific phospholipase C solubilized G2 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 G2 molecular form of acetylcholinesterase (AChE), its distribution, and the mode of attachment to chromaffin cells. Our studies indicate that a substantial fraction of the G2 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 G2 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.