Dynamic patches of membrane proteins
Yael Lavi 1, Michael Edidin 2 and Levi A. Gheber 3*
1 Ben Gurion University
2 Johns Hopkins Univ.
3 Ben-Gurion University of the Negev
* To whom correspondence should be addressed. E-mail: glevi{at}bgu.ac.il.
Submitted on April 26, 2007
Revised on May 17, 2007
Accepted on 28 June 2007
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Abstract |
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We test here a previously proposed hypothesis about lateral heterogeneity of cell membranes, a model predicting heterogenity is maintained by a combination of delivery and intake of molecules with barriers to lateral free diffusion. To test the validity of the model, we observed GFP-tagged MHC-I patches on the plasma membrane of mouse fibroblasts, using TIRFM in real time. The dynamic characterization revealed the life course of these patches is comprised of delivery of molecules at a short instant, followed by a slow, exponential decay, corresponding to diffusion of the molecules over dynamic barriers to free lateral diffusion. The characteristic lifetime of the patches, extracted from the measurements, is approximately 30 s, in excellent agreement with the predictions of the model.
