For a cell to survive, any damage to its plasma membrane must be rapidly repaired. Repair often involves fusion of organelles with the plasma membrane, but the process is poorly understood. On , Anna and Paul McNeil report that tethering – the physical interaction of two membranes destined for fusion – of yolk granules occurs early in the repair of starfish oocyte plasma membrane and identify a multisubunit tethering complex responsible. When the plasma membrane of echinoderm eggs is disrupted, yolk granules fuse homotypically to form large patch granules. These fuse heterotypically with the damaged plasma membrane in a calcium-dependent manner. The authors show that yolk granules form large aggregates when isolated in an appropriate buffer but that a mildly chaotropic salt wash prevents granule tethering. The salt wash contains a complex of at least seven proteins that can restore granule tethering and the formation of large patch granules. Thus, by promoting the formation of large patch granules, tethering may be an initial step in the repair of large plasma membrane disruptions.
