Isolated or biologically pure taste receptors comprised of at least one T1R2 and T1R3 polypeptide and compositions containing are provided. These taste receptors specifically bind and/or are specifically activated by sweet taste stimuli such as natural and artificial sweetener compounds. These taste receptors are useful in screening assays for identifying compounds that elicit or modulate (enhance or inhibit) sweet taste. These compounds can be used as additives and flavorants to improve the taste of compositions for human or animal consumption. In preferred embodiments, the T1R2/T1R3 receptor will be comprised of human T1R2/human T1R3 expressed in association with a suitable G protein, preferably Ga.sub.a15.