Recent insights into mammalian ER–PM junctions

ER–PM junctions are subcellular sites where the endoplasmic reticulum (ER) and the plasma membrane (PM) are kept in close appositions, providing a platform for inter-organelle contact. These membrane contact sites are important for many physiological functions in mammalian cells, including excitation–contraction coupling, store-operated Ca ²⁺ entry, and non-vesicular transfer of lipids between the ER and the PM. Here we review recent insights into the 3D structure and spatial organization of ER–PM junctions in mammalian cells as well as molecular mechanisms underlying the formation and functions of mammalian ER–PM junctions.