  The Yang algebra was proposed a long time ago as a generalization of the
Snyder algebra to the case of curved background spacetime. It includes as
subalgebras both the Snyder and the de Sitter algebras and can therefore be
viewed as a model of noncommutative curved spacetime. A peculiarity with
respect to standard models of noncommutative geometry is that it includes
translation and Lorentz generators, so that the definition of a Hopf algebra
and the physical interpretation of the variables conjugated to the primary ones
is not trivial. In this paper we consider the realizations of the Yang algebra
and its $\kappa$-deformed generalization on an extended phase space and in this
way we are able to define a Hopf structure and a twist.
