Kursula, 2015). The fact that Phe415 and the proximal Leu414 are involved in a core-buried hydrophobic cluster suggests that the entire loop is less dynamic. In general, solvent accessibility of the OLF β-propeller central cavity appears to be a shared feature as exhibited by the presence of a high density of bound water molecules in the available structures of OLF domains (Donegan et al., 2014; Han and Kursula, 2015; Jackson et al., 2015, Pronker et al., 2015, and this study). Furthermore, most of the Ca2+-binding residues in LPHN3-OLF are conserved – or conservatively substituted – in the OLF family, in particular those having their side chain involved in the ion coordination. Although our open-state structure was solved with higher-than-physiological amount of Mg2+, gliomedin-OLF (Han and Kursula, 2015) was crystallized with sub-physiological amount of Na+, indicating that Na+ likely exchanges in vivo.
