Regulation mechanism of the lateral diffusion of band 3 in erythrocyte membranes by the membrane skeleton.
Mechanisms that regulate the movement of a membrane spanning protein band 3 in erythrocyte ghosts were investigated at the level of a single or small groups of molecules using single particle tracking with an enhanced time resolution (0.22 ms). Two-thirds of band 3 undergo macroscopic diffusion: a band 3 molecule is temporarily corralled in a mesh of 110 nm in diameter, and hops to an adjacent mesh an average of every 350 ms. The rest (one-third) of band 3 exhibited oscillatory motion similar to that of spectrin, suggesting that these band 3 molecules are bound to spectrin. When the membrane skeletal network was dragged and deformed/translated using optical tweezers, band 3 molecules that were undergoing hop diffusion were displaced toward the same direction as the skeleton. Mild trypsin treatment of ghosts, which cleaves off the cytoplasmic portion of band 3 without affecting spectrin, actin, and protein 4.1, increased the intercompartmental hop rate of band 3 by a factor of 6, whereas it did not change the corral size and the microscopic diffusion rate within a corral. These results indicate that the cytoplasmic portion of band 3 collides with the membrane skeleton, which causes temporal confinement of band 3 inside a mesh of the membrane skeleton.
Department of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
M
M
Tomishige
Y
Y
Sako
A
A
Kusumi
D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D003599:Cytoskeleton / Q000502:physiology; D004058:Diffusion; D004910:Erythrocyte Membrane / Q000737:chemistry; D004912:Erythrocytes / Q000502:physiology*; D017979:Gold Colloid / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D018715:Microscopy, Video; D013049:Spectrin / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
D001457:Anion Exchange Protein 1, Erythrocyte; D017979:Gold Colloid; D008565:Membrane Proteins; D013049:Spectrin; D014357:Trypsin