Expression and Localization of PRiMA-linked globular form acetylcholinesterase in vertebrate neuromuscular junctions.

Acetylcholinesterase (AChE) is well known to process different molecular forms via the distinct interacting partners. Proline-rich membrane anchor (PRiMA)-linked tetrameric globular AChE (G4 AChE) is mainly found in the vertebrate brain; however, recent studies from our laboratory have suggested its existence at neuromuscular junctions (nmjs). Both muscle and motor neuron express AChE at the nmjs. In muscle, the expression of PRiMA-linked AChE is down-regulated during myogenic differentiation and by motor neuron innervation. As compared with muscle, spinal cord possessed higher total AChE activity and contained PRiMA-linked AChE forms. The spinal cord expression of this form increased during development. More importantly, PRiMA-linked G4 AChE identified as aggregates localized at nmjs. These findings suggest that the restricted localization of PRiMA-linked G4 AChE at the nmjs could be contributed by the pre-synaptic motor neuron and/or the post-synaptic muscle fiber.