All members of the EPI64 subfamily of TBC/RabGAPs also have GAP activities towards Ras

Hiroyuki Nagai, Sayaka Yasuda, Yusuke Ohba, Mitsunori Fukuda, Takeshi Nakamura

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The importance of interconnective signalling networks between distinct GTPases and their regulators is being recognized. EPI64C/TBC1D10C/carabin, a haematopoietically enriched GTPase-activating protein (GAP) for Rab35, has been shown to exhibit RasGAP activity. Owing to the diverged Rab specificities among the EPI64 members (EPI64A-C) and the relatively weak sequence conservation between EPI64A/B and EPI64C in their catalytic TBC domains, it is difficult to predict whether EPI64A and B will also have RasGAP activities. Therefore, in this study, we examined the RasGAP activities of all three EPI64 subfamily members. We found that EPI64A-C exhibited in vivo GAP activities towards Ras using three independent methods, spectrofluorometry with Förster resonance energy transfer (FRET) sensors, the Bos' pull-down assay and time-lapse FRET imaging. EPI64A and B were predominantly localized at the periphery of COS-7 cells. In COS-7 cells, confocal FRET imaging showed that H-Ras activity was higher at the Golgi than at the plasma membrane. Thus, we propose that EPI64A and B, which are ubiquitously expressed members of the EPI64 subfamily, inactivate Ras and certain Rabs at the periphery of cells.

Original languageEnglish
Pages (from-to)283-288
Number of pages6
JournalJournal of Biochemistry
Issue number3
Publication statusPublished - 2013 Mar


  • FRET
  • RabGAP
  • Ras
  • interconnective signalling
  • small G proteins


Dive into the research topics of 'All members of the EPI64 subfamily of TBC/RabGAPs also have GAP activities towards Ras'. Together they form a unique fingerprint.

Cite this