Stollberg, Jes and Fraser, Scott E. (1988) Acetylcholine Receptors and Concanavalin A-Binding Sites on Cultured Xenopus Muscle Cells: Electrophoresis, Diffusion, and Aggregation. Journal of Cell Biology, 107 (4). pp. 1397-1408. ISSN 0021-9525 http://resolver.caltech.edu/CaltechAUTHORS:20120615-151102136
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Using digitally analyzed fluorescence videomicroscopy, we have examined the behavior of acetylcholine receptors and concanavalin A binding sites in response to externally applied electric fields. The distributions of these molecules on cultured Xenopus myoballs were used to test a simple model which assumes that electrophoresis and diffusion are the only important processes involved. The model describes the distribution of concanavalin A sites quite well over a fourfold range of electric field strengths; the results suggest an average diffusion constant of ~2.3 X 10^(-9) cm^2/s. At higher electric field strengths, the asymmetry seen is substantially less than that predicted by the model. Acetylcholine receptors subjected to electric fields show distributions substantially different from those predicted on the basis of simple electrophoresis and diffusion, and evidence a marked tendency to aggregate. Our results suggest that this aggregation is due to lateral migration of surface acetylcholine receptors, and is dependent on surface interactions, rather than the rearrangement of microfilaments or microtubules. The data are consistent with a diffusion-trap mechanism of receptor aggregation, and suggest that the event triggering receptor localization is a local increase in the concentration of acetylcholine receptors, or the electrophoretic concentration of some other molecular species. These observations suggest that, whatever mechanism(s) trigger initial clustering events in vivo, the accumulation of acetylcholine receptors can be substantially enhanced by passive, diffusion-mediated aggregation.
|Additional Information:||© 1988 Rockefeller University Press. Received 30 November 1987; revised 21 January 1988. We thank Drs. Darwin Berg and Stanley Halvorsen for advice and aid in the fluorescent labeling of α-Bgt. This work was supported by a grant from the Monsanto Corporation, a National Institutes of Health (NIH) Training grant (HD07029) (J. Stollberg), and by a McKnight Scholar Award (S. Fraser).|
|Official Citation:||Acetylcholine receptors and concanavalin A-binding sites on cultured Xenopus muscle cells: electrophoresis, diffusion, and aggregation. J Stollberg and S E Fraser J Cell Biol 1988 107:1397-1408. Published October 1, 1988, doi:10.1083/jcb.107.4.1397|
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|Deposited On:||18 Jun 2012 17:11|
|Last Modified:||26 Dec 2012 15:20|
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