Endoplasmic reticulum: Membrane contact sites

This paper presents a review of modern data on the functional designation of membrane contact sites (MCSs) of endoplasmic reticulum. Problems of traffic of lipids and calcium in are discussed. It is to be emphasized that the function of MCSs is not yet clear, while the mechanism providing contact of two membranes (the problem of “anchors”) remains poorly studied. Data are discussed that testify in favor of MCSs being able to participate both in selective traffic of lipids and in free diffusion of any small molecule (apparently, up to 1.5 kDa) and ions between cell compartments that are in contact.