  We have measured the current-voltage characteristics of a Josephson junction
with tunable Josephson energy $E_J$ embedded in an inductive environment
provided by a chain of SQUIDs. Such an environment induces localization of the
charge on the junction, which results in an enhancement of the zero-bias
resistance of the circuit. We understand this result quantitatively in terms of
the Bloch band dynamics of the localized charge. This dynamics is governed by
diffusion in the lowest Bloch band of the Josephson junction as well as by
Landau-Zener transitions out of the lowest band into the higher bands. In
addition, the frequencies corresponding to the self-resonant modes of the SQUID
array exceed the Josephson energy $E_J$ of the tunable junction, which results
in a renormalization of $E_J$, and, as a consequence, of the effective
bandwidth of the lowest Bloch band.
