Prediction of pore-lining residues from sequence mapped onto native crystal structures. Homotetrameric calcium-gated potassium channel MthK (left, 1LNQ) bottom-up view; no false positives were predicted. Homodimeric molybdate transporter ModB2C2 (centre, 2ONK) top-down view. Homotetrameric AMPA-subtype glutamate receptor (3KG2, right) bottom-up view. The pore identified by Pore-Walker is shown by yellow spheres, while residues correctly predicted as pore-lining are shown in green (true positives), incorrectly predicted as pore-lining are shown in orange (false positives), correctly predicted as non-pore-lining are shown in grey (true negatives) and incorrectly predicted as non-pore-lining are shown in magenta (false negatives).