Different membrane-bound forms of acetylcholinesterase are present at the cell surface of hepatocytes

Authors

  • Alejandra PERELMAN,

    1. Molecular Neurobiology Unit, Department of Cell Biology, Faculty of Biological Sciences, Catholic University of Chile, Santiago
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  • Enrique BRANDAN

    Corresponding author
    1. Molecular Neurobiology Unit, Department of Cell Biology, Faculty of Biological Sciences, Catholic University of Chile, Santiago
      Correspondence to E. Brandan, Molecular Neurobiology Unit, Department of Cell Biology, Faculty of Biological Sciences, Catholic University of Chile, PO Box 114-D, Santiago, Chile
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Correspondence to E. Brandan, Molecular Neurobiology Unit, Department of Cell Biology, Faculty of Biological Sciences, Catholic University of Chile, PO Box 114-D, Santiago, Chile

Abstract

In the present study we have determinated the acetylcholinesterase molecular forms present in rat liver hepatocytes; we have also studied the association of acetylcholinesterase with the cell surface of the hepatocytes. Subcellular fractionation indicated that rough endoplasmic reticulum and plasma-membrane-enriched fractions contains G4 and G2 acetylcholinesterase forms bound to membranes. Hepatocytes incubated with phosphatidylinositol-specific phospholipase C released about 70% of the surface acetylcholinesterase. Sedimentation analysis showed that all the solubilized acetylcholinesterase activity comes exclusively from a G2 dimer. The G4 hydrophobic form of acetylcholinesterase accounts for the additional cell-surface activity. The existence of these two forms of acetylcholinesterase on the surface of hepatocytes was further established by analyzing the phosphatidylinositol-specific phospholipase C sensitivity-of the acetylcholinesterase molecular forms present in isolated rat liver plasma membranes.

Abbreviation
Ptdlns

phosphatidylinositol

Enzymes
 

β-Galactosidase (EC 3.2.1.23)

 

acetylcholinesterase (EC 3.1.1.7): catalase (EC 1.11.1.6)

 

butyrlcholinesterase (EC 3.1.1.8)

 

alcohol dehydrogenase (EC 1.1.1.1)

 

PtdIns-specific phospholipase C (EC 3.1.4.3)

 

alkaline phosphatase (EC 3.1.3.1)

 

glucose-6-phosphatase (EC 3.1.3.9)

Ancillary