[en] A non-local parameterization of the proton-nucleus optical potential is presented. This new parameterization is based on the premise that the effective mass has a simple linear density dependence, and that the kinetic energy term in the Schroedinger equation for nucleons contains a spin dependence which, while it can be ignored for the free case, becomes important when interactions are present. A connection is made with the Dirac equation, and applications to deuteron scattering and proton coupled-channel elastic scattering are discussed. (orig.)