Solution
= Solution
The exterior free-substrate <equation> gives $B_e=J$ at <steady state>. Thus $k_+s_ec_e-k_-p_e=J$, and
$$
\boxed{p_e=\frac{s_ec_e}{K}-\frac J{k_-}.}
$$
The sign of the current term is opposite to the interior relation because <substrate> is supplied to the exterior and removed from the interior. Nonnegative occupancies are selected by the complete steady transport solution and compatible <substrate> totals.