||Bacteria Escherichia coli
||Gabel CV, Berg HC. The speed of the flagellar rotary motor of Escherichia coli varies linearly with protonmotive force. Proc Natl Acad Sci U S A. 2003 Jul 22 100(15):8748-51. p.8751 left columnPubMed ID12857945
||"...[assuming] tight coupling, the
speed–pmf relation measured here demonstrates a simple ohmic
current–pmf relation, also indicative of such channels. If (i) two
protons are used per mechanical step of a single torque generating
unit (ref 1), (ii) each one travels through a separate
channel (ref 14), (iii) there are ˜50 such steps per revolution (rev)
(ref 15), and (iv) the motor spins at 380Hz at zero load (ref 3), then the
flux through each channel is ˜50H+/rev × 380Hz=1.9×10^4H+/s."
||"This result is about the same as the current through an
open, ˜30-fS voltage-gated proton channel (ref 13): 4.5 fA (at 150mV) ˜2.8?10^4H+/s. Both of these fluxes are much smaller
than those observed in other ion channels."