Localization of Proline-Rich Membrane Anchor (PRiMA)-associated acetylcholinesterase in vertebrate neuromuscular junctions

Proline-rich membrane anchor (PRiMA) is an important molecule to organize acetylcholinesterase (AChE; EC 3.1.1.7) into tetrameric globular form (G4) and to anchor the complex into plasma membrane [1]. G4 AChE is not only the dominant form of enzyme in the central nervous system but also presents in the peripheral nervous system where it exerts its hydrolytic function [2]. Although G4 AChE is not the major form of AChE in muscle, its existence is tightly controlled. Several studies have revealed that the level of G4 AChE is controlled by the dynamic activity of skeletal muscles. In mammals, fast-twitch muscles contain a high amount of G4 form whereas slow-twitch muscles contain a much smaller amount [2]. Studies also suggested that the expression of PRiMA, as well as PRiMA-associated G4 AChE, in muscle is suppressed by muscle regulatory factors, muscular activity and nerve-derived trophic factor [3]. In order to determine the possible role of PRiMA-associated G4 AChE at the neuromuscular junctions (nmjs), anti-PRiMA polyclonal antibody recognizing the cytoplasmic domain was generated. Rat muscles were analyzed for the expression and localization of PRiMA-associated G4 AChE