The ER (endoplasmic reticulum) consists of the nuclear envelope and a peripheral network of membrane sheets and tubules. Two classes of the evolutionarily conserved ER membrane proteins, reticulons and REEPs (receptor expression-enhancing proteins)/DP1 (deleted in polyposis locus 1)/Yop1 (YIP 1 partner), shape high-curvature ER tubules. In mammals, four members of the reticulon family and six members of the REEP family have been identified so far. In the present paper we report that Arl6IP1(ADP-ribosylation factor-like 6 interacting protein 1), an anti-apoptotic protein specific to multicellular organisms, is a potential player in shaping the ER tubules in mammalian cells. Arl6IP1, which does not share an overall primary sequence homology with reticulons, harbours reticulon-like short hairpin transmembrane domains and binds to atlastin, a GTPase that mediates the formation of the tubular ER network. Overexpression of Arl6IP1 induced extensive tubular structures of the ER and excluded a luminal protein. Furthermore, overexpression of Arl6IP1 stabilized the ER tubules, allowing the cells to maintain the ER tubules even in the absence of microtubules. Arl6IP1 constricted liposomes into tubules. The short hairpin structures of the transmembrane domains were required for the membrane-shaping activity of Arl6IP1. The results of the present study indicate that Arl6IP1 has the ability to shape high-curvature ER tubules in a reticulon-like fashion.
- ADP-ribosylation factor-like 6 interacting protein 1 (Arl6IP1)
- endoplasmic reticulum (ER)
- membrane-shaping protein
- receptor expression-enhancing protein/deleted in polyposis locus 1/YIP 1 partner (REEPs/DP1/Yop1)
- reticulon-homology domain (RHD)
Abbreviations: Arl6IP1, ADP-ribosylation factor-like 6 interacting protein 1; BS3, bis(sulfosuccinimidyl) suberate; DOPC, 1,2-dioleoyl-sn-glycero-3-phosphocholine; DP1, deleted in polyposis locus 1; ER, endoplasmic reticulum; FAM134B, family with sequence similarity 134, member B; HA, haemagglutinin; HEK, human embryonic kidney; Lnp1, Lunapark family member 1; mAb, monoclonal antibody; OG, n-octyl-β-D-glucopyranoside; pAb, polyclonal antibody; PDI, protein disulfide isomerase; REEP, receptor expression-enhancing protein; RHD, reticulon homology domain; Vapa, vesicle-associated membrane protein-associated protein A; Yop1, YIP 1 partner
- © The Authors Journal compilation © 2014 Biochemical Society