Rate limited active transport of calcium.


KINETIC pmp {
        ~ cabulk <-> cam                (1/tau, 1/tau)
        ~ cam + pump <-> capump         (k1, k2)
        ~ capump <-> cao + pump         (k3, k4)
        ica_pmp = 2*FARADAY*(f_flux - b_flux)

        ~ cam << -(ica) : there is a problem here

        COMPARTMENT width {cam} : volume in (um)
        COMPARTMENT 1 {pump capump} : area is dimensionless
        COMPARTMENT 1(m) {cao cabulk}
}