title: Identification and characterization of TMEM33 as a reticulon-binding protein.
abstract: Endoplasmic reticulum (ER) is an organelle that has an elaborate and continuous membrane system composed of sheet-like cisternae and a network of interconnected tubules. The ER tubules are shaped by reticulons, a conserved ER membrane protein family. However, how the membrane-shaping activity is regulated remains to be elucidated. To understand the mode of action of reticulons, we isolated TMEM33, a conserved protein harboring three transmembrane domains, as a reticulon 4C-binding protein by affinity chromatography. In addition to reticulon 4C, TMEM33 binds to reticulon 1A, -2B, -3C and a reticulon homology domain-containing protein Arl6IP1. Exogenously expressed TMEM33 localizes at both the ER membrane and the nuclear envelope. Exogenously expressed TMEM33 co-localizes with exogenously expressed reticulon 4C well at the ER sheets and partially at the ER tubules. Exogenously expressed TMEM33 suppresses the exogenously expressed reticulon 4C-induced tubulation of ER. These results suggest that TMEM33 has a potency to suppress the membrane-shaping activity of reticulons, thereby regulating the tubular structure of ER.
authors.affiliation: Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017 Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Urade
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.forename: Yonson
authors.initials: Y
authors.lastname: Ku
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sakisaka
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000737:chemistry; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D007163:Immunosorbent Techniques; D008565:Membrane Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D009185:Myelin Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D000070798:Nogo Proteins; D009685:Nuclear Envelope / Q000737:chemistry; D011993:Recombinant Fusion Proteins; D013552:Swine; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D009185:Myelin Proteins; D000070798:Nogo Proteins; C000603199:RTN4 protein, human; D011993:Recombinant Fusion Proteins; C000602045:transmembrane protein 33, human
keywords: ER tubules; Reticulon; TMEM33