8.A.108.  The Curature-stabilizing Protein YOP1 (YOP1) Family 

The endoplasmic reticulum is a dynamic network of interconnected membrane tubules. Powers et al. 2017 reconstituted a dynamic tubular membrane network with purified endoplasmic reticulum proteins. Proteoliposomes containing the membrane-fusing GTPase Sey1p (1.N.5.1.6) and the curvature-stabilizing protein Yop1p from Saccharomyces cerevisiae formed a tubular network upon addition of GTP. The tubules rapidly fragment when GTP hydrolysis by Sey1p is inhibited, indicating that network maintenance requires continuous membrane fusion and that Yop1p favours the generation of highly curved membrane structures. Sey1p also forms networks with other curvature-stabilizing proteins, including reticulon and receptor expression-enhancing proteins (REEPs) from different species. Atlastin, the vertebrate orthologue of Sey1p, forms a GTP-hydrolysis-dependent network on its own, serving as both a fusion and curvature-stabilizing protein. These results show that organelle shape can be generated by a surprisingly small set of proteins and represents an energy-dependent steady state between formation and disassembly (Powers et al. 2017).

This family belongs to the .



Powers, R.E., S. Wang, T.Y. Liu, and T.A. Rapoport. (2017). Reconstitution of the tubular endoplasmic reticulum network with purified components. Nature 543: 257-260.


TC#NameOrganismal TypeExample

The ER curvature-stabilizing protein, YOP1, of 180 aas and 4 probable TMSs in a 2 + 2 arrangement (Powers et al. 2017).

YOP1 of Saccharomyces cerevisiae (Baker's yeast)


Uncharacterized receptor expression-enhancing protein 3-like isoform X2 of 229 aas and 3 putative TMSs.

UP of Neolamprologus brichardi


Uncharacterized protein of 221aas and 3 TMSs

UP of Sarcophaga bullata


Uncharacterized protein of 197 aas and 3 TMSs

UP of Aphanomyces invadans


Uncharacterized protein of 161 aas and 3 TMSs.

UP of Caenorhabditis elegans


Uncharacterized protein of 270 aas and 3 TMSs

UP of Malassezia vespertilionis


S-phase cyclin A-associated protein in the endoplasmic reticulum, isoform X1 of 415 aas and 3 N-terminal TMSs in a 1 + 2 TMS arrangement.

Cyclin A of Sesamum indicum