Open AccessCirculation of the Plasma Membrane inDictyostelium
Author(s) -
Carmen AguadoVelasco,
Mark S. Bretscher
Publication year - 1999
Publication title -
molecular biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.463
H-Index - 225
eISSN - 1939-4586
pISSN - 1059-1524
DOI - 10.1091/mbc.10.12.4419
Subject(s) - biology , endocytic cycle , dictyostelium discoideum , endocytosis , internalization , microbiology and biotechnology , clathrin , membrane , axenic , biophysics , dictyostelium , vesicle , biochemistry , receptor , bacteria , genetics , gene
We have developed a fluorimetric assay with the use of the dye FM1-43 to determine the rate at which Dictyostelium amoebae endocytose their surface membrane. Our results show that they do so about once each 4-10 min. A clathrin null mutant takes its surface up only approximately 30% more slowly, showing that this membrane uptake cannot be caused by clathrin-coated vesicles. Surprisingly, Ax2 and its parent, NC4, which differ in their rates of fluid-phase internalization by approximately 60-fold, take up their surfaces at the same rates. These results show that, in axenic cells, the uptake of fluid and of surface area are separate processes. The large activity of this new endocytic cycle in both Ax2 and NC4 amoebae appears capable of delivering sufficient new surface area to advance the cells' fronts during migration.