Endosomal Sorting

The ER gets in on an endocytic sorting act

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Science  16 Jan 2015:
Vol. 347, Issue 6219, pp. 245
DOI: 10.1126/science.347.6219.245-c

Endosomes are organelles that carry protein cargo from the plasma membrane and the extracellular fluid into cells. Although endosomes closely associate with the endoplasmic reticulum (ER) in cells, scientists don't understand why. Rowland et al. now identify the ER as an unexpected player in the sorting of cargo in the endosome and when endosomes divide (fission). Studying this process in mammalian cells, the authors found that an ER tubule crosses over the endosomal membrane, forming a stable contact at positions where endosomes first constrict and then divide. Such ER wrapped-endosomal contact sites prevent cargo from diffusing inappropriately. Interfering with ER dynamics reduced the efficiency of endosome fission.

Cell 159, 1027 (2014)

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