Paper Report for: Noureddine_2007_J.Biol.Chem_282_3487
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Title: Assembly of acetylcholinesterase tetramers by peptidic motifs from the proline-rich membrane anchor, PRiMA: competition between degradation and secretion pathways of heteromeric complexes Noureddine H, Schmitt C, Liu W, Garbay C, Massoulie J, Bon S Ref: Journal of Biological Chemistry, 282:3487, 2007 : PubMed
The membrane-bound form of acetylcholinesterase (AChE) constitutes the major component of this enzyme in the mammalian brain. These molecules are hetero-oligomers, composed of four AChE catalytic subunits of type T (AChE(T)), associated with a transmembrane protein of type 1, called PRiMA (proline-rich membrane anchor). PRiMA consists of a signal peptide, an extracellular domain that contains a proline-rich motif (14 prolines with an intervening leucine, P4LP10), a transmembrane domain, and a cytoplasmic domain. Expression of AChE(T) subunits in transfected COS cells with a truncated PRiMA, without its transmembrane and cytoplasmic domains (P(stp54) mutant), produced secreted heteromeric complexes (T4-P(stp54)), instead of membrane-bound tetramers. In this study, we used a series of deletions and point mutations to analyze the interaction between the extracellular domain of PRiMA and AChE(T) subunits. We confirmed the importance of the polyproline stretches and defined a peptidic motif (RP4LP10RL), which induces the assembly and secretion of a heteromeric complex with four AChE(T) subunits, nearly as efficiently as the entire extracellular domain of PRiMA. It is noteworthy that deletion of the N-terminal segment preceding the prolines had little effect. Interestingly, short PRiMA mutants, truncated within the proline-rich motif, reduced both cellular and secreted AChE activity, suggesting that their interaction with AChE(T) subunits induces their intracellular degradation.
        
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Noureddine H, Schmitt C, Liu W, Garbay C, Massoulie J, Bon S (2007) Assembly of acetylcholinesterase tetramers by peptidic motifs from the proline-rich membrane anchor, PRiMA: competition between degradation and secretion pathways of heteromeric complexes Journal of Biological Chemistry282: 3487-97
Noureddine H, Schmitt C, Liu W, Garbay C, Massoulie J, Bon S (2007) Journal of Biological Chemistry282: 3487-97