from 2 to 30 Å
||Martinac B, Saimi Y, Kung C. Ion channels in microbes. Physiol Rev. 2008 Oct88(4):1449-90. doi: 10.1152/physrev.00005.2008. p.1453 right column bottom paragraphPubMed ID18923187
|| Cruickshank CC, Minchin RF, Le Dain AC, Martinac B. Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli. Biophys J. 199773:1925–1931.  Perozo E, Cortes DM, Sompornpisut P, Kloda A, Martinac B. Open channel structure of MscL and the gating mechanism of mechanosensitive channels. Nature. 2002 418: 942–948.  Perozo E, Kloda A, Cortes DM, Martinac B. Physical principles underlying the transduction of bilayer deformation forces during mechanosensitive channel gating. Nat Struct Biol. 2002 9: 696–703.  Perozo E, Kloda A, Cortes DM, Martinac B. Site-directed spin-labeling analysis of reconstituted Mscl in the closed state. J Gen Physiol. 2001 118: 193–206.PubMed ID9336188, 12198539, 12172537, 11479346
||P.1453 right column bottom paragraph:"...electrophysiological permeation studies using large organic cations (primary source 62) and electronparamagnetic resonance (EPR) spectroscopy combined with cysteine scanning mutagenesis and site-directed spin labeling (SDSL)(primary sources 300–302)."
||P.1453 right column bottom paragraph:"3D structure of the MscL homologue from M. tuberculosis obtained at 3.5 Å resolution shows a homopentameric channel, most likely in a closed state (Fig. 3A) (ref 44). The channel monomer consists of two alpha helical transmembrane (TM) domains, TM1 and TM2, cytoplasmic N- and C-terminal domains and a central periplasmic domain. The channel pore is formed by five transmembrane TM1 helices organized as a tightly packed bundle. At the cytoplasmic side the five helices funnel into a hydrophobic constriction of 2Å functioning as the channel gate. The diameter of the channel pore at the gate expands from 2 to 30 Å during the channel opening as determined by electrophysiological permeation studies using large organic cations (primary source 62) and electronparamagnetic resonance (EPR) spectroscopy combined with cysteine scanning mutagenesis and site-directed spin labeling (SDSL) (primary sources 300–302)."