Cell Biology

Rab-ing Up ER Dynamics

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Science  25 Jan 2013:
Vol. 339, Issue 6118, pp. 375
DOI: 10.1126/science.339.6118.375-a

The endoplasmic reticulum (ER) forms a lace-like network throughout the cytoplasm and exhibits a remarkable ability to remodel itself constantly. How the membranes of the ER can grow, fuse, and divide faithfully and efficiently within cells is not altogether clear, although several factors involved in the regulation of ER dynamics have been identified. Intracellular membrane fusion frequently involves members of the Rab GTPase family. English and Voeltz wanted to determine which Rab was involved in ER dynamics. ER vesicles were isolated from Xenopus egg extracts and shown to be able to form tubular ER networks in vitro. Although several Rab GTPases were associated with these vesicles, only Rab10 localized to ER-associated structures that could move along microtubules and that appeared to be associated with new ER tubules in mammalian tissue culture cells. Reducing the levels of Rab10 or the expression of a Rab10 mutant reduced the number of ER tubules, because of an impaired ability of dynamic ER tubules to grow from and fuse with other ER membranes. Intriguingly, the Rab10 ER tip structures were also associated with a pair of proteins involved in phospholipid synthesis.

Nat. Cell Biol. 10.1038/ncb.2647 (2012).

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