Cell Biology

Under Surveillance

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Science  06 Aug 2010:
Vol. 329, Issue 5992, pp. 610
DOI: 10.1126/science.329.5992.610-a

Proteins and lipids enter the secretory pathway via the endoplasmic reticulum (ER). Within the ER, newly synthesized secretory and membrane proteins are folded and assembled; under conditions of stress that lead to protein misfolding, the ER activates the unfolded protein response pathway. The ER itself is an organelle that the cell cannot generate de novo: During cell division, each daughter cell must be provided with its own complement of ER membranes that serve as a template for future growth. In budding yeast, ER membranes are distributed between the mother cell and the daughter bud by the actin cytoskeleton. Babour et al. have studied ER partitioning in dividing yeast cells under stress and discovered a surveillance pathway that helps to ensure that the daughter cell receives a functional complement of ER membranes. In stressed cells, signaling by the MAP kinase Slt2 is activated, which helps to delay cytokinesis and prevents the delivery of ER to the growing bud. In cells lacking Slt2 kinase, a stressed and therefore functionally compromised ER is transmitted to the daughter cell, leading to the death of both mother and daughter.

Cell 142, 256 (2010).

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