Cell Biology

MAPK and Golgi Structure Regulation

Science's STKE  03 Jul 2001:
Vol. 2001, Issue 89, pp. tw3
DOI: 10.1126/stke.2001.89.tw3

Activation of MAP kinase (MAPK) is thought to require phosphorylation of both a critical tyrosine and threonine residue. However, unmodified or partially phosphorylated MAPK can still regulate certain targets. These include a transcription factor, a phosphatase, and a DNA-modifying enzyme. Now add Golgi to the list. Golgi fragmentation occurs during mitosis to facilitate its equal distribution to daughter cells. Cha and Shapiro show morphologically and biochemically that MAP kinase that is phosphorylated only on the tyrosine residue associates with Golgi membranes in mammalian cells during entry and exit from mitosis. Overexpression of activated MAPK kinase increased Golgi disruption, but coexpression of a mutant form of MAPK that lacks the critical tyrosine residue inhibited this effect. The data imply a possible functional role for tyrosine-phosphorylated MAPK in regulating mitotic Golgi structure through a mechanism that is independent of its kinase activity.

H. Cha, P. Shapiro, Tyrosine-phosphorylated extracellular signal-regulated kinase associates with the Golgi complex during G2/M phase of the cell cycle: Evidence for regulation of Golgi structure. J. Cell Biol. 153, 1355-1367 (2001). [Abstract] [Full Text]