  Deep-inelastic scattering at low Bjorken x and elastic vector meson
electroproduction are analyzed on the basis of the off-shell s-channel
unitarity. We discuss behavior of the total cross-section of virtual
photon-proton scattering and obtain, in particular, that the exponent in the
power-like dependence of $\sigma^{tot}_{\gamma^* p}$ is related to the
interaction radius of a constituent quark. The explicit mass dependence of the
exponent in the power energy behavior of the vector meson electroproduction has
been obtained. Angular distributions at large momentum transfers are
considered. The energy dependence of the total cross-section of
$\gamma^*\gamma^*$-interactions is also obtained.
