gate /gāt/ , 1. n., an electronic circuit that passes a pulse only when a signal (the gate pulse) is present at a second input. 2. n., a mechanism for opening or closing a protein channel in a cell membrane, regulated by a signal such as increased concentration of a neurotransmitter, change in electrical potential, or physical binding of a ligand molecule to the protein to cause a conformational change in the protein molecule. 3. v., to open and close selectively and function as a gate.
