Amphiphilic, glycophosphatidylinositol-specific phospholipase C (PI-PLC)-insensitive monomers and dimers of acetylcholinesterase

Abstract

1. In a recent study, we distinguished two classes of amphiphilic AChE dimers inTorpedo tissues: class I corresponds to glycolipid-anchored dimers and class II molecules are characterized by their lack of sensitivity to PI-PLC and PI-PLD, relatively small shift in sedimentation with detergent, and absence of aggregation without detergent. 2. In the present report, we analyze the amphiphilic or nonamphiphilic properties of globular AChE forms in T₂₈ murine neural cells, rabbit muscle, and chicken muscle. The molecular forms were identified by sucrose gradient sedimentation in the presence and absence of detergent and analyzed by nondenaturing charge-shift electrophoresis. Some amphiphilic forms showed an abnormal electrophoretic migration in the absence of detergent, because of the retention of detergent micelles. 3. We show that the amphiphilic monomers (G ₁ ^a ) from these tissues, as well as the amphiphilic dimers (G ₂ ^a ) from chicken muscle, resemble the class II dimers ofTorpedo AChE. We cannot exclude that these molecules possess a glycolipidic anchor but suggest that their hydrophobic domain may be of a different nature. We discuss their relationships with other cholinesterase molecular forms.