The Coulomb blockade effect in a mesoscopic double-barrier p-i-n junction is reported. The electron and hole injection into the central QW of a p-n junction is achieved via resonant tunneling. We present a theoretical model that describes the device operation. When the device is biased with a constant voltage source the model predicts the observation of Coulomb staircase in the current-voltage characteristics. When an additional square wave modulation signal is applied, turnstile operation is achieved. The experimental evidence for Coulomb staircase effect and turnstile operation is presented.