  Using the framework of collinear factorization in perturbative QCD (pQCD), we
analyze the recent data of the LHCb and ALICE collaborations on exclusive
photoproduction of J/{\psi} in ultraperipheral pp and AA collisions,
respectively. We demonstrate that the simultaneous analysis of the proton and
Pb data allows us to reduce the ambiguity of the pQCD description of the
$\gamma p \to J/\psi p$ and $\gamma A \to J/\psi p$ cross sections and, hence,
to place additional constraints on the gluon distributions in the nucleon and
nuclei at small x. We also make predictions for the cross section of coherent
exclusive photoproduction of J/{\psi} in nucleus-nucleus ultraperipheral
collisions accompanied by the electromagnetic excitation of nuclei and the
subsequent neutron emission.
