A simple inhomogeneous model of protein dielectric properties is discussed. A protein in solution is modeled as a collection of polarizable dipoles in a cavity embedded inside a dielectric medium. The intrinsic polarizabilities of 20 amino acids are assumed to be portable to all proteins in nature. A reasonable set of these polarizability values has been obtained by comparing dielectric fluctuations from molecular dynamics simulations with model calculations. The results are consistent within a data set of three small proteins.