gate

1. To close an ion channel by electrical ( e.g., membrane potential) or chemical ( e.g., neurotransmitter) action. 2. Action of a special nerve fiber to block the transmission of impulses through a synapse, e.g., gating of pain impulses at synapses in the dorsal horns. 3. A device which can be switched electronically to control the passage of a signal. 4. To use a physiological signal, such as an ECG, to trigger an event such as an x-ray exposure or to partition continuously collected data. See gated radionuclide angiocardiography. SEE ALSO: cardiac gating. [O.E. geat]

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gate 'gāt n a molecule or part of a molecule (as an amino acid sequence in a protein) that acts (as by a change in conformation) in response to a stimulus to permit or block passage through a cell membrane

gate vt, gat·ed; gat·ing to control passage through a cell membrane by way of (a specific channel) by supplying a specific stimulus <a transmembrane ion channel gated by the neurotransmitter acetylcholine> see ligand-gated, voltage-gated

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(gāt) 1. an electronic circuit that passes a pulse only when a signal (the gate pulse) is present at a second input; called also gate circuit. 2. a mechanism for opening or closing a 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 channel protein to cause a conformational change in the protein molecule. 3. to open and close selectively and function as a gate.