Here, there, and everywhere: The importance of ER membrane contact sites

Some of the molecular machineries that regulate membrane tethering have now been identified, and thus MCSs can now be ascribed functions.

In recent years, the involvement of MCSs in lipid and ion transport has been confirmed and some of the molecules and mechanisms involved in these processes have been pinpointed.

Novel functions for MCSs, such as their crucial role in regulating organelle distribution and division, have also been identified.

Moreover, it is becoming apparent that interorganelle communication is highly integrated in and subject to homeostatic regulation.

For example, the establishment and regulation of ER-mitochondria and mitochondria-vacuole MCSs are interdependent and appear to respond to nutritional cues (22, 25, 27, 29).

Notably, MCSs are linked to human diseases. Among the handful of proteins identified that specifically regulate MCS functions, a high proportion are mutated in a variety of diseases (127–129).