  We study the impact of differential isolated-photon+jet cross sections
measured in proton-proton collisions at a center-of-mass energy of sqrt{s} = 7
TeV on the parton distribution functions (PDF) of the proton. Next-to-leading
order perturbative QCD (pQCD) calculations complemented with the NNPDF2.1
parton densities, and a Bayesian PDF reweighting method are employed. We find
that although the current data provide only mild constraints to the parton
densities, future gamma-jet measurements with reduced experimental
uncertainties can improve our knowledge of the gluon density over a wide range
of parton fractional momenta x as well as of the quarks at low-x.
