8.A.109.1.5
The Endoplasmic Reticular (ER) three way tubular junctions, consisting of three known proteins, TMCC3, Atlastin-2 and Lunapark (Wisesa et al. 2019). See family description for details regarding TMCC3. Atlastin-2 is a GTPase, tethering membranes through formation of trans-homooligomers and mediating homotypic fusion of ER membranes. It functions in ER tubular network biogenesis (Hu et al. 2009, Wang et al. 2016). Lunapark (LNPK, LNP), with 2 TMSs, is an ER-shaping membrane protein that plays a role in determining ER morphology (Breuss et al. 2018). It is involved in the stabilization of nascent three-way ER tubular junctions within the ER network (Moriya et al. 2013, Shemesh et al. 2014, Chen et al. 2015, Wang et al. 2016). It may also play a role as a curvature-stabilizing protein within the three-way ER tubular junction network (Shemesh et al. 2014). It may also be involved in limb development as well as central nervous system development (Breuss et al. 2018). A longer homolog (see TC# 8.A.1109.1.6) with 653 aas and 2 C-terminal TMSs (TMCC1). TMCC1 is upregulated in gliomas, and its overexpression indicates a poor prognosis for disease oucome. Knockdown of TMCC1 inhibited cell proliferation and induced apoptosis. TMCC1 induces cell migration and invasion by promoting the epithelial-mesenchymal transition (EMT) (Gao et al. 2022). Translation of secretome mRNAs occurs preferentially near lysosomes on ER marked by the ER junction-associated protein, Lunapark. Knockdown of Lunapark reduces the extent of secretome mRNA translation without affecting translation of other mRNAs (Choi et al. 2023).