A Tether is a Tether is a Tether: Tethering at Membrane Contact Sites

Membrane contact sites enable interorganelle communication by positioning organelles in close proximity using molecular "tethers." With a growing understanding of the importance of contact sites, the hunt for new contact sites and their tethers is in full swing. Determining just what is a tether has proven challenging. Here, we aim to delineate guidelines that define the prerequisites for categorizing a protein as a tether. Setting this gold standard now, while groups from different disciplines are beginning to explore membrane contact sites, will enable efficient cooperation in the growing field and help to realize a great collaborative opportunity to boost its development.