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Specific taste buds on the tongue help in experiencing different tastes like sweet, sour, bitter, and umami. The tongue has small sensory organs called the papillae. The papillae possess small hair-like projections called microvilli that include the taste buds.

GPCRs transduce signals for the basic tastes like sweet, bitter, umami, and the flavor kokumi.The taste GPCRs are located on the specific taste receptor cells of the taste buds.

The type I taste GPCRs, also called TAS1R, are the sweet taste receptors, heterodimeric in structure. Type II are the bitter taste receptors with a monomeric structure.

G-alpha Gustducin, G-beta3, and G-gamma 13 are heterotrimeric G proteins that couple to taste GPCRs (sweet, umami, and bitter).

It initiates a series of signal transduction cascades involving phospholipase C-2 activating, production of inositol-1,4,5-trisphosphate, and IP3-dependent Ca²⁺release from the endoplasmic reticulum.

The increased intracellular calcium then activates transient receptors for the potential firing and release of induced ATP that signals the brain to detect the taste, sweet, bitter, or umami.

Thus, if there is a mutation in the molecules of this or any other related signaling pathway, the mice may lose tastes like sweet, bitter, or umami. There will not be any change in the tastes like sour or salty as they do follow any signaling pathway.