Before revision:  Our theory is also applied to study the intrinsic noise structure of stochastic gene expression in coupled gene circuits and a complete decomposition of noise in terms of five different biophysical origins is provided.
After revision:  Our theory is also applied to study the intrinsic noise structure of stochastic gene expression in coupled gene expression noise in a coupled gene circuit and a complete decomposition of noise in terms of five different biophysical origins is provided.