By combining biochemical studies (including protein-protein and protein-lipid binding studies of native or of purified, recombinant components) with fluorescence-based microscopy techniques applied to cellular in vivo systems we were able to elaborate novel and important aspects about how cargo recognition, coat polymerization and membrane deformation are coordinated during the generation of transport carriers.
The formation of transport carriers on different subcellular membranes is coupled to the local generation of distinct species of phosphoinositides (PIs). PI(4,5)P2 (cyan) supports endocytic events at the plasma membrane, whereas PI(4)P (green) and PI(3)P (red) are predominantly synthesized during budding from Golgi membranes and from organelles of endosomal origin, respectively. Different PIs in turn facilitate membrane translocation of adaptor and accessory proteins, which are crucial for cargo recognition, membrane deformation and budding.
Kahlfeldt, N., Vahedi-Faridi, A., Schäfer, J.G., Krainer, G., Keller, S., Saenger, W., Haucke, V. & Krauss, M. (2009) Molecular basis for the association of PIPKI-p90 with the clathrin adaptor AP-2. J Biol Chem. 285, 2734-2749.
Haucke, V. & Krauss, M. (2009) Shaping membranes for endocytosis. Rev. Physiol. Biochem. Pharmacol. (in press)
Krauss M., Jia, J., Roux, A., Beck, R., Wieland, F.T., De Camilli, P. & Haucke, V. (2008). Arf1-GTP-induced tubule formation suggests a function of Arf family proteins in curvature acquisition at sites of vesicle budding. J. Biol. Chem. 283, 27717-23.
Krauss, M. & Haucke, V. (2007). Phosphoinositide-metabolizing enzymes at the interface between membrane traffic and cell signalling. EMBO Rep. 8, 241-246.
Krauss, M. & Haucke, V. (2007). Regulators of membrane traffic and protein function. FEBS Lett. 581, 2105-2111.
Krauss, M., Kukhtina, V., Pechstein, A. & Haucke, V. (2006). Stimulation of PIPK type I-mediated PI(4,5)P2 synthesis by endocytic AP-2µ adaptor cargo complexes. Proc. Natl. Acad. Sci., 103, 11934-11939.
Höning, S., Ricotta, D., Krauss, M., Späte, K., Spolagore, B., Motley, A., Robinson, M., Haucke, V. & Owen, D.J. (2005). Phosphatidylinositol-(4,5)-bisphosphate regulates sorting signal recognition by the clathrin-associated adaptor complex AP2. Mol. Cell 19, 519-531.
Krauss, M., Kinuta, M., Wenk, M.R., De Camilli, P., Takei, K. & Haucke, V. (2003) ARF6 stimulates clathrin/AP-2 recruitment to synaptic membranes by activating phosphatidylinositol phosphate kinase type Igamma. J. Cell. Biol. 162, 113-124.