Fig. 3: Alternative models for MFN2-mediated ER−mitochondria tethering

a The scheme represents the classical view of MFN2 as a positive modulator of ER−mitochondria juxtaposition. In this model, MFN2 on ER membrane engages MFN2 or MFN1 on OMM, mediating the tethering between the two organelles. b The scheme represents the model of MFN2 as a negative modulator of ER−mitochondria juxtaposition. According to this view, MFN2 on both the ER and the OMM interacts with and sequesters still unknown tethering subunits (left), hindering their assembling into a functional tethering complex (represented on the right)