The intracellular Golgi apparatus was believed to be a fixed structure that processed proteins for secretion in an assembly-line fashion. But two papers in November 12 Journal of Cell Biology, show that the entire Golgi apparatus is a dynamic structure and suggest that most, if not all, Golgi protein elements cycle through endoplasmic reticulum (ER) in interphase cells.

Suzanne Miles and colleagues at Virginia Tech, Blacksburg, US, compared the effect of protein inhibition and ER exit blocking on the distribution of 12 different proteins from the Golgi apparatus, including glycosyltransferases and putative matrix proteins. They observed a redistribution of Golgi proteins away from the nucleus only in the presence of ER exit blockers but not in the presence of protein synthesis inhibitors (J Cell Biol 2001, 155:543-556).

"These results suggest that maintenance of a juxtanuclear Golgi apparatus requires protein cycling per se, rather than replacement of...