- apoptosis
- programmed cell death
- autocrine signal
- signal that is sent and received by the same or similar nearby cells
- autoinducer
- signaling molecule secreted by bacteria to communicate with other bacteria of its kind and others
- cell-surface receptor
- cell-surface protein that transmits a signal from the exterior of the cell to the interior, even though the ligand does not enter the cell
- chemical synapse
- small space between axon terminals and dendrites of nerve cells where neurotransmitters function
- cyclic AMP (cAMP)
- second messenger that is derived from ATP
- cyclic AMP-dependent kinase
- (also, protein kinase A, or PKA) kinase that is activated by binding to cAMP
- diacylglycerol (DAG)
- cleavage product of PIP2 that is used for signaling within the plasma membrane
- dimer
- chemical compound formed when two molecules join together
- dimerization
- (of receptor proteins) interaction of two receptor proteins to form a functional complex called a dimer
- endocrine cell
- cell that releases ligands involved in endocrine signaling (hormones)
- endocrine signal
- long-distance signal that is delivered by ligands (hormones) traveling through an organism's circulatory system from the signaling cell to the target cell
- enzyme-linked receptor
- cell-surface receptor with intracellular domains that are associated with membrane-bound enzymes
- extracellular domain
- region of a cell-surface receptor that is located on the cell surface
- G-protein-linked receptor
- cell-surface receptor that activates membrane-bound G-proteins to transmit a signal from the receptor to nearby membrane components
- growth factor
- ligand that binds to cell-surface receptors and stimulates cell growth
- inhibitor
- molecule that binds to a protein (usually an enzyme) and keeps it from functioning
- inositol phospholipid
- lipid present at small concentrations in the plasma membrane that is converted into a second messenger; it has inositol (a carbohydrate) as its hydrophilic head group
- inositol triphosphate (IP3)
- cleavage product of PIP2 that is used for signaling within the cell
- intercellular signaling
- communication between cells
- internal receptor
- (also, intracellular receptor) receptor protein that is located in the cytosol of a cell and binds to ligands that pass through the plasma membrane
- intracellular mediator
- (also, second messenger) small molecule that transmits signals within a cell
- intracellular signaling
- communication within cells
- ion channel-linked receptor
- cell-surface receptor that forms a plasma membrane channel, which opens when a ligand binds to the extracellular domain (ligand-gated channels)
- kinase
- enzyme that catalyzes the transfer of a phosphate group from ATP to another molecule
- ligand
- molecule produced by a signaling cell that binds with a specific receptor, delivering a signal in the process
- mating factor
- signaling molecule secreted by yeast cells to communicate to nearby yeast cells that they are available to mate and communicating their mating orientation
- neurotransmitter
- chemical ligand that carries a signal from one nerve cell to the next
- paracrine signal
- signal between nearby cells that is delivered by ligands traveling in the liquid medium in the space between the cells
- phosphatase
- enzyme that removes the phosphate group from a molecule that has been previously phosphorylated
- phosphodiesterase
- enzyme that degrades cAMP, producing AMP, to terminate signaling
- quorum sensing
- method of cellular communication used by bacteria that informs them of the abundance of similar (or different) bacteria in the environment
- receptor
- protein in or on a target cell that bind to ligands
- second messenger
- small, non-protein molecule that propagates a signal within the cell after activation of a receptor causes its release
- signal integration
- interaction of signals from two or more different cell-surface receptors that merge to activate the same response in the cell
- signal transduction
- propagation of the signal through the cytoplasm (and sometimes also the nucleus) of the cell
- signaling cell
- cell that releases signal molecules that allow communication with another cell
- signaling pathway
- (also signaling cascade) chain of events that occurs in the cytoplasm of the cell to propagate the signal from the plasma membrane to produce a response
- synaptic signal
- chemical signal (neurotransmitter) that travels between nerve cells
- target cell
- cell that has a receptor for a signal or ligand from a signaling cell