Glossary
Afferent	Neuron or nerve fiber that carries signals from peripheral sensory receptors to the central nervous system.
Autocrine	Referring to the action of a transmitter or hormone onto the same cell from which it was secreted.
Ecto-ATPase	An enzyme that degrades extracellular ATP; associated with the extracellular face of the plasma membrane of some taste bud cells.
GPCR	G protein–coupled receptor; integral plasma membrane proteins with 7 transmembrane domains; detect and signal neurotransmitters, hormones, sensory and other stimuli.
Gustation	The sense of taste; beginning with excitation of cells in taste buds and leading to perception of taste qualities (sweet, bitter, etc.).
Gustducin	Heterotrimeric G protein that includes a taste-selective Gα subunit, α-gustducin.
Pannexin	A family of ion channels (Panx1, 2, 3) related to the gap junction–forming connexin proteins; pannexins may only form hemichannels and transfer molecules from cytoplasm to extracellular space.
Paracrine	Referring to the action of a transmitter or hormone onto cells adjacent to or near the cell from which it was secreted.
Sensory code	The pattern of action potentials in sensory nerves that denotes the quality, intensity, duration, etc., of a sensory stimulus.
Somatosensory	The sense of pain, temperature, touch, pressure, texture (and other tactile stimuli).
T1Rs	A family of taste GPCRs (T1R1, R2, R3) that detect sweet or umami tastants; they function as heterodimers, e.g., T1R2 plus T1R3.
T2Rs	A family of taste GPCRs that detect bitter tastants; there are 20–40 members in different species.
Tastants	Compounds that elicit taste.
Taste GPCR	Families of GPCRs that are expressed in taste bud cells and bind sweet, bitter, or umami tastants.
Umami taste	A Japanese term (“good taste”), used for the taste of certain amino acids (especially glutamate), nucleotides (esp. IMP, GMP). Roughly translates as “savory”.