Four ways in which the lateral mobility of specific plasma membrane proteins can be restricted.

The proteins can self-assemble into large aggregates (such as bacteriorhodopsin in the purple membrane of Halobacterium) (A)；they can be tethered by interactions with assemblies of macromolecules outside (B) or inside (C) the cell; or they can interact with proteins on the surface of another cell (D).

这些蛋白质可以自组装成大的聚集物（如盐细菌紫色膜中的细菌视紫质）(a)；它们可以通过与(b)或(c)内部的大分子集合的相互作用连接；或者它们可以与另一个细胞表面的蛋白质相互作用(d)。