  We study the action of space-time symmetries on quantum fields in the
presence of small departures from locality determined by dynamical gravity. It
is shown that, under such relaxation of locality, the symmetries of the theory
cannot be described within the usual framework of Lie algebras but rather in
terms of non-co-commutative Hopf algebras or "quantum groups". Similar
"quantizations" of space-time symmetries are expected to emerge in the
low-energy limit of certain quantum gravity models and have been used to
describe the symmetries of various non-commutative space-times. Our result
provides an intuitive characterization of the mechanism that could lead to the
emergence of deformed co-products in models of quantum relativistic symmetries.
