Rab5 is a member of the large family of small GTPases involved in membrane trafficking. Two genetically encoded sensors were developed to visualize Rab5 in its GTP-bound conformation in living cells. Rab5-binding fragments of Rabaptin5 or early endosomal antigen 1 (EEA.1) were fused to yellow fluorescent protein (YFP) and used in the fluorescent resonance energy transfer (FRET) assay together with Rab5-tagged cyan fluorescent protein (CFP). The presence of energy transfer between CFP-Rab5 and YFP-Rab5 binding fragments detected by sensitized FRET microscopy has validated the utility of these generated sensors to visualize the localization of GTP-bound Rab5. GTP-bound Rab5 was found in endosomes, often concentrated in distinct microdomains. Molecular architecture of the Rab5 microdomains was analyzed by three-chromophore FRET (3-FRET) microscopy, utilizing YFP, CFP, and monomeric red fluorescent proteins (mRFP.l). The results of the 3-FRET analysis suggest that GTP-bound Rab5 is capable of oligomerization and present in multiprotein complexes.
|Number of pages
|Methods in Enzymology
|Published - 2005
Bibliographical noteFunding Information:
This work was supported by grants from National Cancer Institute, National Institute of Drug Abuse (A.S.), and American Cancer Society (A.S. and E.G.), and a postdoctoral fellowship from the American Heart Association (to E.G.).
ASJC Scopus subject areas
- Molecular Biology