I am facing some difficulties to detect D1R by western-blotting in plasma membrane fractions from renal cortex. I have used 2 primary antibodies (from Alpha Diagnostics and Chemicon) and tried several dilutions but none as functioned. I load 8-10Ķg of protein and I canít visualize any band in the membrane. Does anybody have any suggestion regarding the use of these antibodies in plasma membrane fraction? I follow a standard protocol but could it be necessary to do any additional step in the case of membrane fractions?