Final answer:
A heterodimer in taste receptors is when two different receptor proteins form a functional complex, or dimer, which is particularly involved in the detection of sweet, bitter, and umami tastes through G protein-coupled receptors.
Step-by-step explanation:
A heterodimer in taste receptors refers to the interaction between two different receptor proteins that come together to form a functional complex, also known as a dimer. This can be observed in the way taste receptors work, especially for the sweet, bitter, and umami tastes. The molecules responsible for these tastes bind to G protein-coupled receptors (GPCRs), which often involve the dimerization of these receptors to function properly. For example, when sweet-tasting molecules like glucose, fructose, or artificial sweeteners such as aspartame and sucralose bind to these GPCRs, they trigger a signal transduction system that leads to the depolarization of the gustatory cell, generating nerve impulses that are perceived as sweet taste.