title: Functional relationship between CABIT, SAM and 14-3-3 binding domains of GAREM1 that play a role in its subcellular localization.
abstract: GAREM1 (Grb2-associated regulator of Erk/MAPK1) is an adaptor protein that is involved in the epidermal growth factor (EGF) pathway. The nuclear localization of GAREM1 depends on the nuclear localization sequence (NLS), which is located at the N-terminal CABIT (cysteine-containing, all in Themis) domain. Here, we identified 14-3-3ε as a GAREM-binding protein, and its binding site is closely located to the NLS. This 14-3-3 binding site was of the atypical type and independent of GAREM phosphorylation. Moreover, the binding of 14-3-3 had an effect on the nuclear localization of GAREM1. Unexpectedly, we observed that the CABIT domain had intramolecular association with the C-terminal SAM (sterile alpha motif) domain. This association might be inhibited by binding of 14-3-3 at the CABIT domain. Our results demonstrate that the mechanism underlying the nuclear localization of GAREM1 depends on its NLS in the CABIT domain, which is controlled by the binding of 14-3-3 and the C-terminal SAM domain. We suggest that the interplay between 14-3-3, SAM domain and CABIT domain might be responsible for the distribution of GAREM1 in mammalian cells.
authors.affiliation: Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Nishino
authors.affiliation: Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Matsunaga
authors.affiliation: Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan. Electronic address: hkonishi@pu-hiroshima.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Konishi
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D051380:GRB2 Adaptor Protein / Q000737:chemistry / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; C543678:GAREM1 protein, human; D051380:GRB2 Adaptor Protein
keywords: 14-3-3; Adaptor protein; CABIT domain; Nuclear localization; SAM domain