Ferritin of 173 aas and possibly 1 TMS.  Globular ferritin displays excellent membrane-insertion capacity and stable transmembrane ionic current owing to its hydrophobic four-fold channels and hydrophilic three-fold channels. The ionic current rectification and voltage-gating characteristics were discovered in single-ferritin ionic current measurement (Yin et al. 2025). Notably, the ferritin was used as a nanopore sensor, by which the high resolution discrimination of L-cysteine, L-homocysteine, and cysteine-containing dipeptides with the assistance of equivalent Cu²⁺ was achieved. The mechanistic studies by multiple controlled experiments and quantum mechanics/all-atom/coarse-grained multiscale MD simulations reveal that analytes are synergistically captured by His114, Cys126, and Glu130 within the C3 channel, causing blockage signals. The promising ferritin nanopore sensor provides a guide to discovering new protein nanopores without shape restrictions (Yin et al. 2025).