Cell biology: Taxi service for lipids

With its role in intracellular protein transport already known, the FAPP2 protein has now also been implicated in lipid transfer and synthesis. What is more, these two FAPP2-mediated events seem to be linked.

The cellular pathways mediating the secretion of proteins such as hormones and antibodies were first described by George Palade and colleagues¹ in the 1960s. Many gaps have been filled since the heyday of their work, but the basic principles remain as originally described. Proteins that travel along the secretory pathway begin their life in the endoplasmic reticulum. They then move to the Golgi complex, where they are processed further and sorted for transport to their final destinations. The vehicles for protein transport are membrane vesicles, which bud off from one compartment and fuse with the next. By contrast, synthesis and transport of membrane lipids has received less attention. This is, in part, due to a widespread misperception that lipids are simply the glue that holds proteins in place, and that their own transport within cells has little more than a passive role in secretion. On page 62 of this issue, D'Angelo et al.² challenge this view, showing that there is an unexpected link between lipid biosynthesis and protein secretion.