Between the sheets: a molecular sieve makes myelin membranes

Abstract

Myelin is a lipid-rich, spiraled membrane structure that allows for rapid propagation of action potentials through axons. In this issue, Aggarwal et al. (2011) present evidence that myelin basic protein, essential for myelination by oligodendrocytes, regulates the biosynthesis of myelin membranes by restricting diffusion of membrane-bound proteins into compact myelin.

Figure 1. Mechanism Driving Establishment of Polarity in Myelin Membranes

(A) Myelin basic protein (MBP) resides in compact myelin and blocks the entry of membrane-bound proteins with large cytoplasmic domains (e.g., CNPase), thus establishing asymmetry between compact and noncompact myelin. (B) In the absence of MBP, these proteins can invade compact myelin.