Arl6IP1 has the potency to shape the mammalian ER membrane in a reticulon-like fashion

The endoplasmic reticulum (ER) consists of the nuclear envelope and a peripheral network of membrane sheets and tubules. Two classes of the evolutionally conserved ER membrane proteins, reticulons and REEPs/DP1/Yop1, 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. Here we report that ADP-ribosylation factor-like 6 interacting protein 1 (Arl6IP1), 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 overall primary sequence homology with reticulons, harbors reticulon-like short hairpin transmembrane domains and bound to atlastin, a GTPase that mediates formation of tubular ER network. Overexpression of Arl6IP1 induced extensive tubular structures of the ER and excluded a luminal protein from there. 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. These results indicate that Arl6IP1 has the potency to shape high-curvature ER tubules in a reticulon-like fashion.

Source: BJ Cell - November 22, 2013 Category: Biochemistry Authors: Y Yamamoto, A Yoshida, N Miyazaki, K Iwasaki, T Sakisaka Tags: BJ Cell Source Type: research