ER sheets get roughed up.

The molecular machinery that shapes the endoplasmic reticulum's (ER's) membrane into ordered networks of "smooth" tubules and "rough" sheets is poorly defined. Shibata et al. (2010) now report that sheet-inducing proteins, such as Climp-63, are enriched in the "rough" ER by their association with membrane-bound ribosomes, whereas curvature-inducing proteins localize at highly bent edges of membrane sheets.