Figure 3.

Tethering complexes at peroxisome‐ER MCSs. All hitherto identified and potential tethering complexes connect organelle membranes via protein‐protein interactions. The C‐tail‐anchored proxisomal membrane proteins ACBD4 and ACBD5 possess FFAT‐like motifs in their middle domain which interact with N‐terminal major sperm‐binding (MSP) domains of ER‐resident VAPA and VAPB. With MOSPD2, another ER‐resident protein with an MSP domain was recently identified, which interacts with a variety of tether proteins containing FFAT motifs.36 MOSPD1 is another MSP‐domain containing protein with a proposed ER localization.37 Interaction of MOSPD proteins with ACBD4/5 has not yet been experimentally verified. The tail‐anchored membrane protein FIS1 was identified in a tethering complex with ER‐resident BAP31.38 As FIS1 also localizes to peroxisomes,39 the FIS1‐BAP31 tether may also contribute to peroxisome‐ER MCSs