On and Off Membrane Dynamics of the ER-Golgi Tethering Factor p115 In Vivo

BRANDON E, SZUL T, ALVAREZ C, GRABSKI R, BENJAMIN R, KAWAI R, SZTUL E.

MOLECULAR BIOLOGY OF THE CELL

American Society for Cell Biology,

Lugar: Bethesda, MD; Año: 2006 vol. 17 p. 2996 - 2996

1059-1524

p class="abstract">The mechanisms regulating membrane recruitment of the p115 tethering factor in vivo are unknown. Here, we describe cycling of p115 between membranes and cytosol and document the effects of Golgi matrix proteins, Rab1, and soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors (SNAREs) on this process. Rapid membrane/cytosol exchange is shown by swift (t1/2 approximately 20 s) loss of Golgi-localized p115-green fluorescent protein (GFP) after repeated photobleaching of cell periphery and rapid (t1/2 approximately 13 s) fluorescence recovery after photobleaching Golgi-localized p115-GFP. p115 mutant missing the GM130/giantin binding site exhibits analogous fluorescence recovery after photobleaching (FRAP) (t1/2 approximately 13 s), suggesting that GM130 and giantin are not major determinants of p115 membrane dynamics. In contrast, p115-GFP exchanges more rapidly (t1/2 approximately 8 s) in cells expressing the inactive Rab1/N121I mutant, i