N-glycosylation enables high lateral mobility of GPI-anchored proteins at a molecular crowding threshold

作者：Hartel Andreas J W; Glogger Marius; Jones Nicola G; Abuillan Wasim; Batram Christopher; Hermann Anne; Fenz Susanne F; Tanaka Motomu; Engstler Markus^*

来源：Nature Communications, 2016, 7(1): 12870.

DOI：10.1038/ncomms12870

The protein density in biological membranes can be extraordinarily high, but the impact of molecular crowding on the diffusion of membrane proteins has not been studied systematically in a natural system. The diversity of the membrane proteome of most cells may preclude systematic studies. African trypanosomes, however, feature a uniform surface coat that is dominated by a single type of variant surface glycoprotein (VSG). Here we study the density-dependence of the diffusion of different glycosylphosphatidylinositol-anchored VSG-types on living cells and in artificial membranes. Our results suggest that a specific molecular crowding threshold (MCT) limits diffusion and hence affects protein function. Obstacles in the form of heterologous proteins compromise the diffusion coefficient and the MCT. The trypanosome VSG-coat operates very close to its MCT. Importantly, our experiments show that N-linked glycans act as molecular insulators that reduce retarding intermolecular interactions allowing membrane proteins to function correctly even when densely packed.

• 出版日期2016-9