Regulation of contractile vacuole formation and activity in Dictyostelium.

EMBO J

Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093-0380, USA.

Published: August 2008

The contractile vacuole (CV) system is the osmoregulatory organelle required for survival for many free-living cells under hypotonic conditions. We identified a new CV regulator, Disgorgin, a TBC-domain-containing protein, which translocates to the CV membrane at the late stage of CV charging and regulates CV-plasma membrane fusion and discharging. disgorgin(-) cells produce large CVs due to impaired CV-plasma membrane fusion. Disgorgin is a specific GAP for Rab8A-GTP, which also localizes to the CV and whose hydrolysis is required for discharging. We demonstrate that Drainin, a previously identified TBC-domain-containing protein, lies upstream from Disgorgin in this pathway. Unlike Disgorgin, Drainin lacks GAP activity but functions as a Rab11A effector. The BEACH family proteins LvsA and LvsD were identified in a suppressor/enhancer screen of the disgorgin(-) large CV phenotype and demonstrated to have distinct functions in regulating CV formation. Our studies help define the pathways controlling CV function.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2516880PMC
http://dx.doi.org/10.1038/emboj.2008.131DOI Listing

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