title: Dual roles of the N-terminal coiled-coil domain of an Aplysia sec7 protein: homodimer formation and nuclear export.
abstract: Cytohesin family proteins act as guanine nucleotide exchange factors (GEFs) for the ADP-ribosylation factor family of small GTP-binding proteins. Aplysia Sec7 (ApSec7), a member of the cytohesin family in Aplysia, plays key roles in neurite outgrowth in Aplysia neurons. Although ApSec7 has a conserved coiled-coil (CC) domain, its role was not clear. In this study, we found that the CC domain of ApSec7 and ARNO/cytohesin 2 are involved in homodimer formation, leading to efficient plasma membrane targeting of ApSec7 and ARNO/cytohesin 2 in HEK293T cells. Therefore, deletion of the CC domain of ApSec7 and ARNO/cytohesin 2 may result in a loss of dimerization and reduce plasma membrane localization. In addition, the CC domains of ApSec7 and ARNO/cytohesin 2 have partially or fully CRM1-dependent nuclear export signals, respectively. Taken together, our results suggest that the CC domain of cytohesin family proteins, including ApSec7 and ARNO/cytohesin 2, has dual roles in intracellular targeting: increased plasma membrane targeting through homodimer formation and nuclear exclusion through either a CRM1-dependent or a CRM1-independent pathway.
authors: Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea.
authors: Yong-Woo
authors: YW
authors: Jun
authors: Department of Biological Sciences, Korea Institute of Science and Technology (KAIST), Daejeon, Korea.
authors: Seung-Hee
authors: SH
authors: Lee
authors: Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanak-gu, Seoul, Korea.
authors: Jaehoon
authors: J
authors: Shim
authors: Department of Biotechnology and Biological Science, College of Life Science and Nano Technology, Hannam University, Yuseong-daero, Yuseong-gu, Daejeon, Korea.
authors: Jin-A
authors: JA
authors: Lee
authors: Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanak-gu, Seoul, Korea.
authors: Chae-Seok
authors: CS
authors: Lim
authors: Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanak-gu, Seoul, Korea.
authors: Bong-Kiun
authors: BK
authors: Kaang
authors: Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea.
authors: Deok-Jin
authors: DJ
authors: Jang
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia; D002478:Cells, Cultured; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D055503:Protein Multimerization / Q000502:physiology*
chemical_list: D020662:Guanine Nucleotide Exchange Factors
keywords: ARNO/cytohesin 2; Sec7 protein; coiled-coil domain; cytohesin family; dimerization; nuclear export signal