Compartmentalized structure of the plasma membrane for receptor movements as revealed by a nanometer-level motion analysis.

Abstract

Abstract. Movements of transferrin and cz2-macroglobulin receptor molecules in the plasma membrane of cultured normal rat kidney (NRK) fibroblastic cells were investigated by video-enhanced contrast optical microscopy with 1.8 nm spatial precision and 33 ms temporal resolution by labeling the receptors with the ligand-coated nanometer-sized colloidal gold particles. For both receptor species, most of the movement trajectories are of the confined diffusion type, within domains of =0.25/zm 2 (500-700 nm in diagonal length). Movement within the domains is random with a diffusion coefficient .~10 -9 cm2/s, which is consistent with that expected for free Brownian diffusion of proteins in the plasma membrane. The receptor molecules move from one domain to one of the adjacent domains at an average frequency of 0.034 s -1 (the residence time within a domain =29 s), indicating that the plasma membrane is compartmentalized for diffusion of membrane receptors and that long-range diffusion is the result of successive intercompartmental jumps. The macroscopic diffusion coefficients for these two receptor molecules calculated on the basis of the compartment size and the intercompartmental jump rate are =2.4 x 10 -H cm2/s, which is consistent with those determined by averaging the long-term movements of many particles. Partial destruction of the cytoskeleton decreased the confined diffusion mode, increased the simple diffusion mode, and induced the directed diffusion (transport) mode. These results suggest that the boundaries between compartments are made of dynamically fluctuating membrane skeletons (membraneskeleton fence model).uR understanding of the mechanisms that control localization, multimerization, and assembly of membrane proteins in the plasma membrane and their relationships with the membrane function is currently undergoing rapid evolution. Assembly of integral membrane proteins are key steps in the formation of special membrane domains such as coated pits, synapses, and cell-adhesion structures (Dubinsky et al., 1987;Pearse and Robinson, 1990). Oligomerization of integral membrane proteins and receptors are common occurrences in the plasma membrane (Kusumi and Hyde, 1982 and references therein;Ullrich and Schlessinger, 1990;Metzger, 1992), and in many cases are known to be involved in signal transduction in the plasma membrane, such as ligand-induced oligomerization of Fc% Fee, and epidermal growth factor receptors. It has become clear that the non-homogeneous distribution and assembly of membrane proteins in the plasma membrane are, in part,

Single-particle tracking of murine polyoma virus-like particles on live cells and artificial membranes

“…The filaments prevent free diffusion of proteins and complexes with bulky cytoplasmic protrusions. Although such proteins and complexes are free to diffuse within each partition of the grid, intercompartment movement is restricted (4,6,26,29,30). In the picket scenario, bulky cytoplasmic domains are not required for confinement.…”

“…On the basis of SPT and fluorescence recovery after photobleaching studies, several groups have concluded that the plasma membrane is partitioned by actin filaments on the cytosolic surface into nanocompartments that allow rapid local diffusion of proteins and lipids within them but suppress long-range diffusion that involves intercompartment movement (4,6,26). To explain the effects of cortical actin, a membrane skeleton ''fence'' or ''corral'' model and an anchored-transmembrane protein ''picket'' model (4,5,27,28) have been proposed.…”

“…To explain the effects of cortical actin, a membrane skeleton ''fence'' or ''corral'' model and an anchored-transmembrane protein ''picket'' model (4,5,27,28) have been proposed.…”

Visualizing odorant receptor trafficking in living cells down to the single-molecule level

“…Similar domain sizes have been found for NK2R in HEK293 cells (35): Fluorescence recovery after photobleaching experiments revealed domains of radius ϭ 420 Ϯ 80 nm without ligand and 170 Ϯ 50 nm when agonist was bound. The larger domains could arise from confinement by a membrane-skeleton͞cytoskeleton fence structure (32,36) or from long-range protein interactions (31) and might represent a population average of the two larger compartments found here. Because OR17-40 is constitutively internalizing, the smaller domains are likely to correspond to precursors of clathrincoated pits (35,37).…”

Diffusion-limited reactions in G-protein activation: Unexpected consequences of antagonist and agonist competition

“…For the two dimensional reactions in the cell membrane, G-protein activation and receptor phosphorylation, we used values of D = 10 −11 -10 −9 cm 2 /sec (Lee et al, 1993;Sako and Kusumi), SA = 1000 μm 2 , and [G] = 10 -100/μm 2 (Pardo et al, 1997). For G-protein activation we then calculate range for k + of 10 −6 to 10 −3 (#/cell) −1 sec −1 .…”