生体膜のラテラル方向のダイナミックス構造解析

抄録

Proteins are capable of lateral and rotational motion in lipid bilayer membranes. Lateral diffusion of membrane proteins has been studied mainly by the fluorescence photobleaching recovery (FPR) technique, and rotational diffusion by the technique of anisotropy decay of “triplet probes” bound to proteins or by the technique of saturation transfer electron spin resonance (ST-ESR). From these results, it has become clear that motion of proteins in lipid bilayer membranes can be well described as that of a cylindrical particle in a two-dimensional matrix with a viscosity of a few poise.
However, the protein mobility in cell plasma membranes is, in many cases, largely restricted. This restriction would be due to the interaction of the integral protein with the cytoskeletal proteins. As an example, lateral and rotational motion of an anion channel protein band 3, in human erythrocyte membrane is described. In this case, it is suggested that there are two kinds of restriction/regulation mechanisms. One is the anchoring of band 3 to the cytoskeletal protein network, the other is the trapping in a compartment formed with the cytoskeletal proteins. Based on these studies, the character of lateral dynamics of proteins in biomembranes is disucussed.