Cytosolic calcium activates the nonselective cation channel, transient receptor potential cation channel subfamily M member (TRPM5
), causing plasma membrane depolarization, which activates voltage-gated sodium ([Na.sup.+]) channels, resulting in action potential propagation that ultimately causes ATP release through calcium homeostasis modulator 1 (CALHM1), a large pore channel [9, 24-26].
Phospholipase C [beta]2 (PLC[beta]2) is subsequently stimulated, leading to release of intracellular [Ca.sup.2+] and activation of the transient receptor potential channel M5 (TRPM5
Arachidonic acid can function as a signaling modulator by activating the TRPM5
cation channel in taste receptor cells.
Activation of TRPM5
Underlies Thermal Sensitivity of Sweet Taste, 438
Sclafani, "Impact of T1r3 and Trpm5
on carbohydrate preference and acceptance in C57BL/6 mice," Chemical Senses, vol.
The signaling cascade induced by LCFA in taste bud cells showed several similarities with the signal transduction cascade specific for sweet, bitter, and umami taste: GPCR involvement, activation of phospholipase C, calcium signaling, and transient cell depolarization are caused by the opening of the [Na.sup.+]-permeable channel called transient receptor potential melastatin-5 (TRPM5
) [168,171, 172].
Shigeto et al.: GLP-1 stimulates insulin secretion by PKC-dependent TRPM4 and TRPM5
The melastatin subfamily (TRPM) has been subdivided into three subgroups on the basis of sequence homology (TRPM1/TRPM3, TRPM4/ TRPM5
, and TRPM6/7) with TRPM8 and TRPM2 being distinct proteins .
Zhang notes that all three tastes require a protein called Trpm5
, which is impaired by cold temperatures.
G-protein [alpha]-Gustducin and TrpM5
Channel in Solitary Chemosensory Cells are Necessary for the Trigeminal Respiratory Depression Response Elicited by the Bitter Compound Denatonium Benzoate, Marco Tizzano, University of Colorado, Denver, A.
The researchers have also found a second pathway, the peripheral Trpm5
protein pathway -that helps animals sense a bitter taste.
According to the study, the reaction of TRPM5
in our taste buds is much more intense when the temperature of food or fluid is increased, sending a stronger electrical signal to the brain and resulting in an enhanced taste.