Journal of Neuroscience, Vol 1, 1260-1267, Copyright © 1981 by Society for Neuroscience
Cellular localization of the molecular forms of acetylcholinesterase in rat pheochromocytoma PC12 cells treated with nerve growth factor
NC Inestrosa, CG Reiness, LF Reichardt and ZW Hall
In rat pheochromocytoma (PC12) cells treated with nerve growth factor
(NGF), there are several molecular forms of the enzyme acetylcholinesterase
(AChE) which sediment on sucrose density gradients at 4 to 6, 10, and 16 S,
respectively. We have investigated the cellular localization of these forms
in PC12 cells. In order to determine which forms are soluble and which are
membrane bound, we extracted PC12 cells in buffers of various ionic
strengths and detergent compositions. To distinguish internal from external
forms of the enzyme, we examined the effect of di-isopropyl fluorophosphate
and BW284c51 dibromide, membrane-permeable and -impermeable inhibitors of
AChE, respectively, AChE forms in intact cells. We also determined the
susceptibility of the forms in intact cells to collagenase treatment. Based
on these studies, we conclude that the globular G1 and G2 (4 to 6 S) forms
are internal and consist of both soluble and membrane- associated species.
Thirty percent of the G4 (10 S) form is bound to cytoplasmic membrane
structures, while the remainder occurs as an integral component of the
plasma membrane. The asymmetric A12 (16 S) form is also a surface protein
but is extracted by high salt without detergent and is released from intact
cells by collagenase. This form thus contains a collagenous domain and is
located outside of the plasma membrane, where it may be associated with an
extracellular matrix.
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