title: REI-1, a Novel Rab11 GEF with a SH3BP5 domain.
abstract: The small GTPase Rab proteins are key regulators of membrane trafficking. Rab11 is one of the best-characterized molecules among the Rab family proteins and it plays multiple roles in endocytic recycling, exocytosis, and cytokinesis. However, it remains unclear how Rab11 is activated at a precise timing and location and regulates its diverse functions. Specifically, our knowledge of the upstream regulatory factors that activate Rab11 is limited. In this regard, we have identified the RAB-11-interacting protein-1 (REI-1) as a novel guanine nucleotide exchange factor (GEF) for RAB-11 inCaenorhabditis elegans(C. elegans). REI-1 family proteins are conserved among metazoans, and its human homolog, SH3BP5, also exhibits strong GEF activity toward human Rab11. InC. elegans, REI-1 is expressed in the germline and co-localizes with RAB-11 on late-Golgi membranes. The loss of REI-1 impaired the targeting of RAB-11 to the late-Golgi compartment, as well as the recycling endosomes in embryos and further reduced the recruitment of RAB-11 to the cleavage furrow, resulting in the delay of cytokinesis. We suggest that REI-1 is the GEF responsible for regulating RAB-11 localization and function in early embryos.
authors.affiliation: Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University , Maebashi, Gunma, Japan.
authors.forename: Aisa
authors.initials: A
authors.lastname: Sakaguchi
authors.affiliation: Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University , Maebashi, Gunma, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Sato
authors.affiliation: Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University , Maebashi, Gunma, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Sato
keywords: C. elegans; REI; Rab11; SH3BP5; cytokinesis; embryo; guanine nucleotide exchange factor (GEF); small GTPase