Cell membrane functions as a boarder of cell by separating it from the outside environment, and the membrane proteins are the gateways to the cell. Nutrients, ions, waste products, even DNA and proteins are transported into and out of cells by membrane proteins. Membrane proteins involve in many cellular functions including: signaling transduction, cell adhesion, cell motility, transportation, and cell communication. Given their important roles in cell functions, membrane proteins are often considered to be perfect drugs targets. In fact, about two-thirds of approved drugs target membrane proteins, nevertheless, these account for only a very small part of the potential targets. Therefore, membrane protein is still a main focus for new drug discovery.