3B7Z: Crystal Structure of Yeast Sec14 Homolog Sfh1 in Complex with Phosphatidylcholine or Phosphatidylinositol

Sec14, the major yeast phosphatidylinositol (PtdIns)/phosphatidylcholine (PtdCho) transfer protein, regulates essential interfaces between lipid metabolism and membrane trafficking from the trans-Golgi network (TGN). How Sec14 does so remains unclear. We report that Sec14 binds PtdIns and PtdCho at distinct (but overlapping) sites, and both PtdIns- and PtdCho-binding activities are essential Sec14 activities. We further show both activities must reside within the same molecule to reconstitute a functional Sec14 and for effective Sec14-mediated regulation of phosphoinositide homeostasis in vivo. This regulation is uncoupled from PtdIns-transfer activity and argues for an interfacial presentation mode for Sec14-mediated potentiation of PtdIns kinases. Such a regulatory role for Sec14 is a primary counter to action of the Kes1 sterol-binding protein that antagonizes PtdIns 4-OH kinase activity in vivo. Collectively, these findings outline functional mechanisms for the Sec14 superfamily and reveal additional layers of complexity for regulating phosphoinositide homeostasis in eukaryotes.
PDB ID: 3B7ZDownload
MMDB ID: 62560
PDB Deposition Date: 2007/10/31
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.03  Å
Source Organism:
Similar Structures:
Biological Unit for 3B7Z: monomeric; determined by author and by software (PISA)
Molecular Components in 3B7Z
Label Count Molecule
Protein (1 molecule)
Uncharacterized Protein Ykl091c(Gene symbol: YKL091C)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB