title: Kinectin-dependent assembly of translation elongation factor-1 complex on endoplasmic reticulum regulates protein synthesis.
abstract: Kinectin is an integral membrane protein with many isoforms primarily found on the endoplasmic reticulum. It has been found to bind kinesin, Rho GTPase, and translation elongation factor-1delta. None of the existing models for the quaternary organization of the elongation factor-1 complex in higher eukaryotes involves kinectin. We have investigated here the assembly of the elongation factor-1 complex onto endoplasmic reticulum via kinectin using in vitro and in vivo assays. We established that the entire elongation factor-1 complex can be anchored to endoplasmic reticulum via kinectin, and the interacting partners are as follows. Kinectin binds EF-1delta, which in turn binds EF-1gamma but not EF-1beta; EF-1gamma binds EF-1delta and EF-1beta but not kinectin. In vivo splice blocking of the kinectin exons 36 and 37 produced kinectin lacking the EF-1delta binding domain, which disrupted the membrane localization of EF-1delta, EF-1gamma, and EF-1beta on endoplasmic reticulum, similar to the disruptions seen with the overexpression of kinectin fragments containing the EF-1delta binding domain. The disruptions of the EF-1delta/kinectin interaction inhibited expression of membrane proteins but enhanced synthesis of cytosolic proteins in vivo. These findings suggest that anchoring the elongation factor-1 complex onto endoplasmic reticulum via EF-1delta/kinectin interaction is important for regulating protein synthesis in eukaryotic cells.
authors.affiliation: National University Medical Institutes, National University of Singapore, Singapore 117597, Singapore.
authors.forename: Lee-Lee
authors.initials: LL
authors.lastname: Ong
authors.forename: Pao-Chun
authors.initials: PC
authors.lastname: Lin
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Ser-Mien
authors.initials: SM
authors.lastname: Chia
authors.forename: Hanry
authors.initials: H
authors.lastname: Yu
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000235:genetics*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: C088547:KTN1 protein, human; D008565:Membrane Proteins; D020648:Peptide Elongation Factor 1; D021122:Protein Subunits; D012333:RNA, Messenger