1.R.1.1.1
Membrane Contact Site (MCS).  Functions include lipid and ion transport between organelles as well as organelle positioning and division (Wu et al. 2018).
Constituents include:
Seipin, 398 aas and 2 - 4 TMSs, Q96G97.
Protrudin, 411 aas and 4 - 5 TMSs, Q5T4F4.
Spastin (SPAST, ADPSP, FSP2, SPG4), 616 aas, 1 N-terminal TMS, Q9UBP0.
Vesicle-associated membrane protein-associated protein A, (VAPA, VAP33), 249 aas, 1 C-terninal TMS, a member of TC family 9.B.17), Q9P0L0.
Vesicle-associated membane protein associated, VAPB/C (see TC 9.B.17.1.1), 243 aas and 1 C-terminal TMS, O95292.
Dynamin 2 (Dyn2, Dnm2) GTPase, 870 aas, 1 TMS, see TC# 8.A.34.1.4, P50570.
Mitofusin 2 (Mfn2, CPRP1) GTPase, 757 aas, 0 - 2 TMSs, (see TC# 1.N.6.1.2), O95140.
Acyl-CoA binding domain-containing protein 5, ACBD5, 534 aas, 1 C-terminal TMS, Q5T8D3.
Mitofusin; Its heptad repeat domain 1 has membrane destabilization function in mitochondrial fusion (Daste et al. 2018).
PDZ domain-containing protein 8, PDZD8, of 1154 aas, a molecular tethering protein that connects ER and mitochondria membranes and is a shared component of at least two distinct MCSs (Hirabayashi et al. 2017; Elbaz-Alon et al. 2020).  Mfn2 regulates mitochondria and mitochondria-associated endoplasmic reticulum membrane function in neurodegeneration induced by repeated sevoflurane exposure (Zhu et al. 2024).