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8.A.102.  The Reticulon (Reticulon) Family

Primary plant plasmodesmata (PD) arise at cytokinesis when the new cell plate forms. During this process, fine strands of endoplasmic reticulum (ER) are laid down between enlarging Golgi-derived vesicles to form nascent PD, each pore containing a desmotubule, a membranous rod derived from the cortical ER. Members of the reticulon (RTNLB) family of ER-tubulating proteins in Arabidopsis thaliana play a role in the formation of the desmotubule. RTNLB3 and RTNLB6, two RTNLBs present in the PD proteome, are recruited to the cell plate at late telophase, when primary PD are formed, and remain associated with primary PD in the mature cell wall (Knox et al. 2015). Both RTNLBs show significant colocalization at PD. These RTNLBs are mobile at the edge of the developing cell plate where new wall materials are being delivered, but significantly less mobile at its center, where PD are forming. Reticulons are involved in peroxysomal biogenesis (Mast et al. 2016). Reticulon proteins regulate intracellular trafficing in plants (Lee et al. 2011).  RTN3 is directly involved in the ER-constituent trafficking events through dually acting as an essential and important ER-stress sensor, and a trigger for Bcl-2 translocation (Wan et al. 2007). 

Reticulons are within a large family of integral membrane proteins that are ubiquitous in eukaryotes and play a key role in functional remodelling of the endoplasmic reticulum membrane. The reticulon family is especially large in plants, with the Arabidopsis thaliana genome containing twenty-one isoforms. Reticulons vary in length but all contain a conserved C-terminal reticulon homology domain (RHD) that associates with membranes.  The structure of one small homologue has been modeled (Chow et al. 2018).

References associated with 8.A.102 family:

Brooks, R.L., C.S. Mistry, and A.M. Dixon. (2021). Curvature sensing amphipathic helix in the C-terminus of RTNLB13 is conserved in all endoplasmic reticulum shaping reticulons in Arabidopsis thaliana. Sci Rep 11: 6326. 33737685
Chow, M., M. Sklepari, L. Frigerio, and A.M. Dixon. (2018). Bacterial expression, purification and biophysical characterization of the smallest plant reticulon isoform, RTNLB13. Protein Expr Purif 152: 31-39. [Epub: Ahead of Print] 29969670
Hu, J. and T.A. Rapoport. (2016). Fusion of the endoplasmic reticulum by membrane-bound GTPases. Semin Cell Dev Biol 60: 105-111. 27269373
Knox, K., P. Wang, V. Kriechbaumer, J. Tilsner, L. Frigerio, I. Sparkes, C. Hawes, and K. Oparka. (2015). Putting the Squeeze on Plasmodesmata: A Role for Reticulons in Primary Plasmodesmata Formation. Plant Physiol. 168: 1563-1572. 26084919
Lee, H.Y., C.H. Bowen, G.V. Popescu, H.G. Kang, N. Kato, S. Ma, S. Dinesh-Kumar, M. Snyder, and S.C. Popescu. (2011). Arabidopsis RTNLB1 and RTNLB2 Reticulon-like proteins regulate intracellular trafficking and activity of the FLS2 immune receptor. Plant Cell 23: 3374-3391. 21949153
Mallmann, R., K. Ondacova, L. Moravcikova, B. Jurkovicova-Tarabova, M. Pavlovicova, L. Lichvarova, V. Kominkova, N. Klugbauer, and L. Lacinova. (2019). Four novel interaction partners demonstrate diverse modulatory effects on voltage-gated Ca2.2 Ca channels. Pflugers Arch. [Epub: Ahead of Print] 30612149
Mast, F.D., A. Jamakhandi, R.A. Saleem, D.J. Dilworth, R.S. Rogers, R.A. Rachubinski, and J.D. Aitchison. (2016). Peroxins Pex30 and Pex29 Dynamically Associate with Reticulons to Regulate Peroxisome Biogenesis from the Endoplasmic Reticulum. J. Biol. Chem. 291: 15408-15427. 27129769
Wan, Q., E. Kuang, W. Dong, S. Zhou, H. Xu, Y. Qi, and Y. Liu. (2007). Reticulon 3 mediates Bcl-2 accumulation in mitochondria in response to endoplasmic reticulum stress. Apoptosis 12: 319-328. 17191123
Yang, Y. and D.J. Klionsky. (2020). A novel reticulophagy receptor, Epr1: a bridge between the phagophore protein Atg8 and ER transmembrane VAP proteins. Autophagy 1-2. [Epub: Ahead of Print] 33121335