| Primary Identifier | IPR031468 | Type | Domain |
| Short Name | SMP_LBD |
| description | Membrane contacts sites (MCSs), regions where two organelles come in closeproximity to one another, act as molecular hubs for the exchange of smallmolecules (e.g. lipids) and signals (e.g. calcium ions). Synaptotagmin-likeMitochondrial lipid-binding Proteins (SMP) domains are exclusively found atMCSs between different organelles such as endoplasmic reticulum (ER)-Mitochondrion, ER-Plasma membrane (PM) and Nucleus-Vacuole junctions. The SMPdomain is able to homo- or heterodimerize, harbors lipids in a hydrophobiccavity and mediates lipid transfer between the two adjacent bilayersindependently of membrane fusion and fission reactions. SMP proteins arewidespread amongst eukaryotic species with a particular enrichment in plantsand features suggestive of species-specific functional variations. SMP domain-containing proteins have been classified into four broad groups: C2 domainsynaptotagmin-like, PH domain-containing HT-008, PDZK8 and mitochondrialprotein families [, , , , , ].The SMP domain consists of 6 β-strands and 3 helices arranged to form abarrel whose interior is lined almost exclusively by hydrophobic residues. The resulting elongated barrel-shaped cylindrical structureharbors a lateral opening and a central hydrophobic cavity where phospholipidscan bind. It dimerizes in an anti-parallel fashion to form a cylindertraversed by a deep hydrophobic groove [, , ]. The SMP domain belongs to theTULIP (for TUbular LIPid-binding) protein superfamily of lipid transferproteins []. |
