Deciphering a mechanism of membrane permeabilization by α-hordothionin peptide

► Formation of a water-selective pore running through the thionin α-helix core. ► Unfolding of the C-end of the α2-helix opens a pore mouth. ► Highly conserved cysteines and tyrosine line the pore walls. ► Thionin is a small water channel with properties resembling that of aquaporins. ► It is proposed that the thionin water channel delivers water to the bilayer center.