Active transport occurs in the cell membrane. Active transport is when a cell uses energy to transport proteins from one side of the cell membrane to the other side.
Proteins that move within the cell membrane are specific to the protein that each carries. One protein cannot change the type of protein it carries from one side of the cell membrane to the other. The proteins that move during active transport are transporting proteins to help keep the cell functioning properly. The cell membrane has the potential to stop active transport. The proteins being block by the membrane are called inhibitors.