Among the numerous different protein families implicated in control of membrane trafficking are the synaptotagmins. These are large integral membrane proteins that bind to phospholipids and the t-SNAREs syntaxins. Synaptotagmin I and synaptotagmin II are thought to function in neurotransmitter release and lysosomal exocytosis, respectively, but precious little is known about what the other 11 members of this family do. Ronit Sagi-Eisenberg and co-workers have now studied the role of synaptotagmin III, which is expressed in mast cells (see p. 145). Colocalizing the protein with markers proteins such as EEA1 and histamine,they show that it is present on early endosomes and secretory granules. They then use an antisense cDNA approach to reduce synaptotagmin III levels:although this has no effect on uptake of cargo (transferrin) into early endosomes, it does block transport from early endosomes to the perinuclear endocytic recycling compartment (ERC) and also generates enlarged secretory granules. The authors therefore conclude that synaptotagmin III is critical for transport of cargo from early endosomes to the ERC. Furthermore, given the effect on secretory granules, they suggest it is part of a novel mechanism for recycling of material from immature secretory granules to the ERC during their maturation.