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Updated: Jul 15, 2026

Taste Exam: A Brief and Validated Test
Published on: August 17, 2018
Taste-modifying sweet protein, neoculin, is received at human T1R3 amino terminal domain
Ayako Koizumi1, Ken-ichiro Nakajima, Tomiko Asakura
1Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Tokyo, Japan.
Abstract:
This study examines taste reception of neoculin, a Curculigo latifolia sweet protein with taste-modifying activity which converts sourness to sweetness. Neoculin tastes sweet to humans, but not to mice, and is received by the human sweet taste receptor hT1R2-hT1R3. In the present study with calcium imaging analysis of HEK cells expressing human and mouse T1Rs, we demonstrated that hT1R3 is required for the reception of neoculin. Further experiments using human/mouse chimeric T1R3s revealed that the extracellular amino terminal domain (ATD) of hT1R3 is essential for the reception of neoculin. Although T1R2-T1R3 is known to have multiple potential ligand-binding sites to receive a wide variety of sweeteners, the present study is apparently the first to identify the ATD of hT1R3 as a new sweetener-binding region.
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