Vesicle trafficking and cell surface membrane patchiness.
Membrane proteins and lipids often appear to be distributed in patches on the cell surface. These patches are often assumed to be membrane domains, arising from specific molecular associations. However, a computer simulation (Gheber and Edidin, 1999) shows that membrane patchiness may result from a combination of vesicle trafficking and dynamic barriers to lateral mobility. The simulation predicts that the steady-state patches of proteins and lipids seen on the cell surface will decay if vesicle trafficking is inhibited. To test this prediction, we compared the apparent sizes and intensities of patches of class I HLA molecules, integral membrane proteins, before and after inhibiting endocytic vesicle traffic from the cell surface, either by incubation in hypertonic medium or by expression of a dominant-negative mutant dynamin. As predicted by the simulation, the apparent sizes of HLA patches increased, whereas their intensities decreased after endocytosis and vesicle trafficking were inhibited.
Tang
Q
Q
Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Edidin
M
M
D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism; D003198:Computer Simulation; D022162:Cytoplasmic Vesicles / Q000187:drug effects / Q000378:metabolism*; D034281:Dynamins; D004705:Endocytosis / Q000187:drug effects; D005347:Fibroblasts; D005453:Fluorescence; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D015234:HLA-A Antigens / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006982:Hypertonic Solutions / Q000494:pharmacology; D008563:Membrane Lipids / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008863:Microspheres; D008954:Models, Biological; D009154:Mutation; D013696:Temperature; D013997:Time Factors
D002966:Clathrin; D015234:HLA-A Antigens; D006982:Hypertonic Solutions; D008563:Membrane Lipids; D008565:Membrane Proteins; D020558:GTP Phosphohydrolases; D034281:Dynamins