title: BPOZ-2 directly binds to eEF1A1 to promote eEF1A1 ubiquitylation and degradation and prevent translation.
abstract: Bood POZ containing gene type 2 (BPOZ-2), which contains ankyrin repeats, NLS, BTB/POZ domains and LXXLL motifs, is an adaptor protein for the E3 ubiquitin ligase scaffold protein CUL3. We isolated a cDNA encoding eukaryotic elongation factor 1A1 (eEF1A1) as a BPOZ-2 binding protein by screening a human thymus cDNA library using a yeast two-hybrid system. eEF1A1 is essential for translation and is also involved in the 26S proteasome-dependent degradation of misfolded or unfolded proteins. The binding between BPOZ-2 and eEF1A1 was confirmed by pull-down and immunoprecipitation assays in vitro and in vivo, respectively. BPOZ-2 binds to eEF1A1 through the ankyrin repeats and both BTB/POZ domains in BPOZ-2 and Domains I and III in eEF1A1. BPOZ-2 and eEF1A1 over-expressed in HEK 293T cells co-localized as speckles within the cytoplasm. BPOZ-2 promoted eEF1A1 ubiquitylation and degradation, suggesting that eEF1A1 is a substrate of BPOZ-2. BPOZ-2 inhibited GTP binding to eEF1A1 and prevented translation in in vitro translation assay using rabbit reticulocytes.
authors.affiliation: Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan. koiwai@rs.noda.tus.ac.jp
authors.forename: Kotaro
authors.initials: K
authors.lastname: Koiwai
authors.forename: So
authors.initials: S
authors.lastname: Maezawa
authors.forename: Takahide
authors.initials: T
authors.lastname: Hayano
authors.forename: Michiko
authors.initials: M
authors.lastname: Iitsuka
authors.forename: Osamu
authors.initials: O
authors.lastname: Koiwai
mesh_terms: D000818:Animals; D019556:COS Cells; D002417:Cattle; D002460:Cell Line; D002474:Cell-Free System; D002522:Chlorocebus aethiops; D006801:Humans; D016297:Mutagenesis, Site-Directed; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D014176:Protein Biosynthesis; D012097:Repressor Proteins / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism; D014162:Transfection; D020798:Two-Hybrid System Techniques; D054875:Ubiquitination
chemical_list: C402243:ABTB1 protein, human; C094814:EEF1A1 protein, human; D020648:Peptide Elongation Factor 1; D012097:Repressor Proteins; D046988:Proteasome Endopeptidase Complex