Connecting vesicular transport with lipid synthesis: FAPP2.

Next to the protein-based machineries composed of small G-proteins, coat complexes, SNAREs and tethering factors, the lipid-based machineries are emerging as important players in membrane trafficking. As a component of these machineries, lipid transfer proteins have recently attracted the attention of cell biologists for their involvement in trafficking along different segments of the secretory pathway. Among these, the four-phosphate adaptor protein 2 (FAPP2) was discovered as a protein that localizes dynamically with the trans-Golgi network and regulates the transport of proteins from the Golgi complex to the cell surface. Later studies have highlighted a role for FAPP2 as lipid transfer protein involved in glycosphingolipid metabolism at the Golgi complex. Here we discuss the available evidence on the function of FAPP2 in both membrane trafficking and lipid metabolism and propose a mechanism of action of FAPP2 that integrates its activities in membrane trafficking and in lipid transfer. This article is part of a Special Issue entitled Lipids and Vesicular Transport.