Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9886123 | Biochimica et Biophysica Acta (BBA) - General Subjects | 2005 | 6 Pages |
Abstract
We have measured the lateral mobility of individual α5 integrin molecules in ventral plasma membranes of fibroblasts, which were prepared by removal of apical surfaces and nuclei followed by elimination of actin filaments with gelsolin, an actin-severing protein. The cytoplasmic domain of individual integrin molecules was tagged with 100 nm fluorescent polystyrene bead, and motion of the bead was observed and video-recorded. Position of the bead in each frame was determined from the centroid of the fluorescence image, from which plots of the mean-square displacement against time intervals were derived. Within short intervals of time (<100 ms) the mean-square displacement was proportional to the time interval, and the averaged translational diffusion coefficient of (5.3±4.4)Ã10â10 cm2/s was obtained with a broad distribution of (1.3-20)Ã10â10 cm2/s. The broad distribution might reflect the oligomerized state of integrin. The largest diffusion coefficient was comparable to that of lipid molecules previously measured in cells and probably represented the diffusion of a single integrin molecule in the presence of little interference of actin cytoskeleton or extracellular matrix. In longer time intervals (>100 ms) the motion of the bead was confined in an area, the average diameter of which was 410±160 nm. This was similar to the values described in previous reports, in which the motion of other membrane receptors labeled on their extracellular domain was measured in living cells.
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Authors
Hiroaki Hirata, Kazuo Ohki, Hidetake Miyata,