Targeting Acetylcholinesterase to Membrane Rafts

• Published in: The Journal of biological chemistry 2010-04, Vol.285 (15), p.11537-11546
• Main Authors: Xie, Heidi Q., Liang, Dong, Leung, K. Wing, Chen, Vicky P., Zhu, Kevin Y., Chan, Wallace K.B., Choi, Roy C.Y., Massoulié, Jean, Tsim, Karl W.K.
• Format: Article
• Language: English
• Subjects: Acetylcholinesterase; Cholesterol Recognition/Interaction Consensus; Detergent Resistance; Heterogeneity; Lipid/Raft; Membrane Trafficking; Membrane/Proteins; PRiMA; Protein Targeting; Tetrameric Acetylcholinesterase
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.038711

In the mammalian brain, acetylcholinesterase (AChE) is anchored in cell membranes by a transmembrane protein PRiMA (proline-rich membrane anchor). We present evidence that at least part of the PRiMA-linked AChE is integrated in membrane microdomains called rafts. A significant proportion of PRiMA-linked AChE tetramers from rat brain was recovered in raft fractions; this proportion was markedly higher at low rather than at high concentrations of cold Triton X-100. The detergent-resistant fraction increased during brain development. In NG108-15 neuroblastoma cells transfected with cDNAs encoding AChET and PRiMA, PRiMA-linked G4 AChE was found in membrane rafts and showed the same sensitivity to cold Triton X-100 extraction as in the brain. The association of PRiMA-linked AChE with rafts was weaker than that of glycosylphosphatidylinositol-anchored G2 AChE or G4 QN-HC-linked AChE. It was found to depend on the presence of a cholesterol-binding motif, called CRAC (cholesterol recognition/interaction amino acid consensus), located at the junction of transmembrane and cytoplasmic domains of both PRiMA I and II isoforms. The cytoplasmic domain of PRiMA, which differs between PRiMA I and PRiMA II, appeared to play some role in stabilizing the raft localization of G4 AChE, because the Triton X-100-resistant fraction was smaller with the shorter PRiMA II isoform than that with the longer PRiMA I isoform.