Fig. 1

TULIP domains form elongated cylindrical dimers with lateral openings leading to hydrophobic pockets. a Cartoon of head-to-head TULIP dimers. The two slightly conical TULIP domains contain a pocket that accommodates 1 or 2 lipids, with surface openings through which hydrophilic headgroups project. b Structure of Cholesteryl Ester Transfer Protein (CETP, 4EWS_A), showing transparent protein (N- and C- terminal TULIPs coloured blue and red), and space-filling spheres of four bound lipids [6]. c Side and end views of the ribbon structure of SMP domain in Extended Synaptotagmin-2 (4P42), showing the central super-helical β-meander (yellow) that is flanked by partially helical elements (blue preceding and red following) [7]