Endomembrane trafficking of ras: the CAAX motif targets proteins to the ER and Golgi

Cell. 1999 Jul 9;98(1):69-80. doi: 10.1016/S0092-8674(00)80607-8.

Abstract

We show that Nras is transiently localized in the Golgi prior to the plasma membrane (PM). Moreover, green fluorescent protein (GFP)-tagged Nras illuminated motile, peri-Golgi vesicles, and prolonged BFA treatment blocked PM expression. GFP-Hras colocalized with GFP-Nras, but GFP-Kras4B revealed less Golgi and no vesicular fluorescence. Whereas a secondary membrane targeting signal was required for PM expression, the CAAX motif alone was necessary and sufficient to target proteins to the endomembrane where they were methylated, a modification required for efficient membrane association. Thus, prenylated CAAX proteins do not associate directly with the PM but instead associate with the endomembrane and are subsequently transported to the PM, a process that requires a secondary targeting motif.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • CHO Cells
  • COS Cells
  • Cell Line
  • Cell Membrane / metabolism*
  • Cricetinae
  • Dogs
  • Endoplasmic Reticulum / metabolism*
  • Golgi Apparatus / metabolism*
  • Green Fluorescent Proteins
  • Kidney
  • Kinetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Transfection
  • ras Proteins / chemistry
  • ras Proteins / genetics
  • ras Proteins / metabolism*

Substances

  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • ras Proteins