RT Journal Article
SR Electronic
T1 Comparable affinity of RabGDIα to GTP- and GDP-bound forms of Rab7 supports a four-state transition model for Rab7 subcellular localization
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 287516
DO 10.1101/287516
A1 Akane Kanemitsu-Fujita
A1 So Morishita
A1 Svend Kjaer
A1 Mitsunori Fukuda
A1 Giampietro Schiavo
A1 Takeshi Nakamura
YR 2018
UL http://biorxiv.org/content/early/2018/04/02/287516.abstract
AB Endolysosomal system is linked to almost all aspects of a cell’s life and diseases, and Rab7 occupies a critical node in this endocytic degradation pathway. However, there have been conflicting theories about the exact role of Rab7 in membrane trafficking, since some researchers report that Rab7 regulates the trafficking from early to late endosomes, while others have reported its functions in trafficking between late endosomes to lysosomes. In the present study, we have revisited this issue from a new perspective. In COS-7 cells, the GDP-bound Rab7 mutant, T22N, was found to be located on the vesicular membranes as well as in the cytoplasm. On the other hand, the GTPase-deficient Q67L mutant of Rab7 resided in cytoplasm as well as on membranes. Additionally, we found that RabGDI interacted with both GTP and GDP bound forms of Rab7 in vitro. Based on the results we have proposed a four-state transition model for Rab7. This four-state model correlates with our recent findings that Rab7 was initially recruited to macropinosomes in a GDP-bound inactive form and subsequently activated during endocytic maturation in EGF-stimulated COS-7 cells.