Golgi protein FAPP2 tubulates membranes

Abstract

The Golgi-associated four-phosphate adaptor protein 2 (FAPP2) has been shown to possess transfer activity for glucosylceramide both in vitro and in cells. We have previously shown that FAPP2 is involved in apical transport from the Golgi complex in epithelial MDCK cells. In this paper we assign an unknown activity for the protein as well as providing structural insight into protein assembly and a low-resolution envelope structure. By applying analytical ultracentrifugation and small-angle x-ray scattering, we show that FAPP2 is a dimeric protein in solution, having a curved shape 30 nm in length. The purified FAPP2 protein has the capability to form tubules from membrane sheets in vitro. This activity is dependent on the phosphoinositide-binding activity of the PH domain of FAPP2. These data suggest that FAPP2 functions directly in the formation of apical carriers in the trans-Golgi network.membrane tubulation ͉ PH domain ͉ phosphatidylinositol 4-phosphate ͉ trans-Golgi network ͉ small-angle x-ray scattering (SAXS)

C2 domain membrane penetration by group IVA cytosolic phospholipase A2 induces membrane curvature changes

“…The FAPP1 and 2 PH domains require insertion of a turret loop adjacent to the PI(4)P binding pocket ( 42 ) to induce membrane remodeling where the inherent shape of FAPP1 or -2 may also play a critical role ( 30 ). However, unlike the ENTH and BAR domain, elegant models of membrane scaffolding and modes of membrane curvature induction for PH and C2 domains have not been investigated.…”

“…PH domains ( 30 ) and C2 domains ( 32 ) have also been shown to induce membrane curvature changes. The FAPP1 and 2 PH domains require insertion of a turret loop adjacent to the PI(4)P binding pocket ( 42 ) to induce membrane remodeling where the inherent shape of FAPP1 or -2 may also play a critical role ( 30 ).…”

“…been found to induce membrane curvature changes ( 27 ), including the epsin N-terminal homology (ENTH) ( 28 ), bin-amphiphysin-Rvs167 (BAR) ( 29 ), Pleckstrin homology (PH) ( 30 ), Amot coiled-coil homology domain (ACCH) ( 31 ), and C2 domains ( 32 ). Here, we investigate the ability of the isolated C2 domain of cPLA 2 ␣ to induce changes to lipid structure.…”

The periciliary ring in polarized epithelial cells is a hot spot for delivery of the apical protein gp135

“…To generate and maintain this polarity, membrane proteins bound for each membrane are sorted into separate carrier vesicles and their trafficking is tightly regulated (Ellis et al, 2006;Cao et al, 2009;. The asymmetrical distribution of proteins in these cells is essential for epithelial tissues to perform their physiological functions, including the vectorial transport of solutes against steep concentration gradients.…”

Sorting of GPI-anchored proteins from yeast to mammals – common pathways at different sites?

“…Membrane-bending factors such as BAR-domain-containing proteins (Peter et al, 2004) or the insertion of a small amphipathic or hydrophobic wedge to induce membrane asymmetry and curvature (McMahon and Gallop, 2005) are likely to be required. Recently, depletion of four-phosphate-adaptor protein 2 (FAPP2), which contains a hydrophobic wedge in its PH domain, by RNA interference (Cao et al, 2009;Lenoir et al, 2010) was found to result in delayed delivery and/or intracellular accumulation of apical raftassociated proteins (either transmembrane proteins or GPI-APs) in polarized MDCK cells, whereas their basolateral transport was unaffected (Vieira et al, 2005).…”