In turbulent plane Couette flow subject to spanwise anti-cyclonic system rotation there exist both large-scale roll-cell structures that arises due to the Coriolis instability and smaller-scale turbulence. The transport equations of the large-scale and small-scale parts of the Reynolds stress are derived and we decompose the flow field into its large- and small-scale parts using spatial low-pass filtering in order to closely investigate the interaction between the roll cells and the small-scale turbulence.