Making the right contacts

Cell Biology Contacts between the endoplasmic reticulum (ER) and mitochondria mediate key physiological processes such as Ca2+ exchange and lipid biogenesis. In yeast, ER and mitochondria are tethered by a complex of four proteins called ERMES. However, no functional orthologs of these ERMES complex proteins have been identified in metazoans. Hirabayashi et al. identified PDZD8 as a structural and functional ortholog of the yeast ERMES protein MMM1 (see the Perspective by Lombardi and Elrod). PDZD8 was found at ER-mitochondria contact sites and was required for ER-mitochondria tethering in mammalian cells. In neuronal dendrites, PDZD8 regulated synaptically evoked Ca2+ dynamics, which underscores the importance of interorganelle membrane contacts in cell physiology. Science , this issue p. [623][1]; see also p. [591][2] [1]: /lookup/doi/10.1126/science.aan6009 [2]: /lookup/doi/10.1126/science.aaq0141