Table 2. Transport equation at E_rev for transporters with different substrate: ion stoichiometries.

Process	Transport principle	Stoichiometry
Uniport	mSain → mSaout
Symport	mSain + nIbin↔mSaout + nIbout	$E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\left(\text{bn}+\text{am}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{in}}{\left[\text{I}\right]\text{out}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$ When* a = -2, b =1 $E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\left(\text{n}-2\text{m}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{in}}{\left[\text{I}\right]\text{out}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$ When a = 1, b = 2 $E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\left(2\text{n}+\text{m}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{in}}{\left[\text{I}\right]\text{out}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$ When a =0, b = 1 $E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\text{n}}(\text{nlog}\frac{\left[\text{I}\right]\text{in}}{\left[\text{I}\right]\text{out}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$
Antiport	mSaout + nIbin↔mSain + nIbout	$E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\left(\text{bn}+\text{am}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{out}}{\left[\text{I}\right]\text{in}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$ When a = -2, b = 2 $E_{\text{rev}}=\Delta \psi =\frac{-30\text{mV}}{\left(\text{n}-\text{m}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{in}}{\left[\text{I}\right]\text{out}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$ When a = 1, b = 2 $E_{\text{rev}}=\Delta \psi =\frac{-60\text{mV}}{\left(\text{2n}+\text{m}\right)}(\text{nlog}\frac{\left[\text{I}\right]\text{out}}{\left[\text{I}\right]\text{in}}+\text{mlog}\frac{\left[\text{S}\right]\text{in}}{\left[\text{S}\right]\text{out}})$

R is the universal gas constant, T is the temperature (in °K), F is the Faraday constant, a and b are the substrate and ion charges, respectively, Δψis the voltage difference across the membrane, m and n denotes the number of substrate and ions respectively. I, S denote ion and substrate respectively. At equilibrium with conversion to the base 10 log, and approximating RT/F as 60mV.