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TAS2R43

receptor / receptor-tas2r43

TAS2R43 is a subtype of human bitter taste receptor.

On this page (7 sections)
  1. Overview
  2. Sources for this overview (5)
  3. Topic hubs
  4. Follow the connections
  5. Related entries (10)
  6. Measured values (1)
  7. Mechanism and receptors (4)
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Reading the bitterness

TAS2R43 is one of the subtypes of human bitter taste receptors. Activation by lactucin and lactucopicrin found in chicory has been confirmed in receptor assays using cultured cells. In vitro potency (EC50) was approximately 14.9 µM for lactucin, whereas lactucopicrin was approximately 0.46 µM, much more potent. The paper reports that potency decreases in the order: lactucopicrin, lactucin, 11β,13-dihydrolactucin. However, this is the order of potency at the cellular level and does not directly determine the intensity of bitterness of the food as a whole.

This TAS2R43 gene is found to be deleted in many people. A genetic analysis of 946 individuals from 52 populations worldwide found gene copy number ranging from 0 to 2, and the global frequency of the deletion allele reached 0.33. The same study reported that over 20% of participants in Europe lacked this gene. Therefore, the order of potency in cultured cells cannot be directly applied to human populations as a whole.

In fact, the bitterness of caffeine is perceived even by people lacking the TAS2R43 gene (estimated at approximately 18-30% in reviews). This is one example that cannot be fully explained by a single receptor alone. However, it should be noted that this 18-30% figure is an estimate from reviews, and the type of quantity it represents differs from the primary data (0.33 above) showing the frequency of gene deletion itself.

Saccharin sodium 2.5 mM activates TAS2R43-expressing cells. This response was shown to be inhibited in a dose-dependent manner by the aromatic compound (R)-(-)-carvone, which has a menthol-like cooling sensation. In the same experiment, carvone inhibited TAS2R31 as well, but did not inhibit TAS2R50.

Caffeine has been reported to trigger calcium signals at multiple human bitter taste receptors including TAS2R7, TAS2R10, TAS2R14, TAS2R43, and TAS2R46. Within the scope of the abstract, the aromatic compound (R)-citronellal is reported to completely block this caffeine-induced response in TAS2R43-expressing cells. From experiments using multiple receptor agonists of different structures, the same abstract reports that (R)-citronellal was identified as a general allosteric inhibitor of TAS2R43.

Sources for this overview

  1. Overlapping activation pattern of bitter taste receptors affect sensory adaptation and food perception

    Lang R; Lang T; Dunkel A; Ziegler F; Behrens M / 2022 / journal article / full text checked

    Checked for this overview: Verified EC50 and potency ranking of lactucin and lactucopicrin

  2. Copy Number Variation in TAS2R Bitter Taste Receptor Genes: Structure, Origin, and Population Genetics

    Roudnitzky N; Risso D; Drayna D; Behrens M; Meyerhof W; Wooding SP / 2016 / journal article / full text checked

    Checked for this overview: Verified descriptions of deletion allele frequency 0.33 and over 20% in Europe / Verified the difference between the 18-30% review estimate and primary data

  3. The Taste of Caffeine

    Poole RL; Tordoff MG / 2017 / review / full text checked

    Checked for this overview: Verified review description that caffeine tastes bitter even in individuals with gene deletion

  4. Menthol-like cooling compounds, including (R)-(-)-carvone, inhibit the human bitter taste receptors for saccharin and acesulfame K

    Saito M; Misaka T / 2025 / journal article / full text checked

    Checked for this overview: Finding that carvone inhibits saccharin response in a dose-dependent manner

  5. The Odorant (R)-Citronellal Attenuates Caffeine Bitterness by Inhibiting the Bitter Receptors TAS2R43 and TAS2R46

    Suess B; Brockhoff A; Meyerhof W; Hofmann T / 2018 / journal article / abstract checked

    Checked for this overview: Finding that citronellal blocks caffeine-induced response

Follow the connections

lactucin →activates→ TAS2R43

caffeine →remains bitter even for peo…→ TAS2R43

saccharin →activates→ TAS2R43

Measured values (1)

KindCompoundTargetValueConditionsSource
receptor EC50lactucinTAS2R4314.9±2.5 µMHEK293 cell assayLang R, 2022

Values are the reported values of each source (with units and conditions). Thresholds and EC50 depend on the panel and method; they are not single true values.

Structured claims — open a section to read each claim's confidence, evidence and limits

Mechanism and receptors (4)

lactucin activates TAS2R43supported

Scope: Receptor assay in a cultured-cell system, in the cited study

Note: Receptor activation alone does not determine the intensity of the food as a whole.

Lactucin activated TAS2R43 with a threshold of 10 uM and an EC50 of 14.9 +/- 2.5 uM. Lactucopicrin was far more potent at the same receptor (threshold 0.1 uM, EC50 0.46 +/- 0.08 uM), and the paper ranks the compounds verbatim as "lactucopicrin exhibiting the highest potency, lactucin with medium potency and 11beta,13-dihydrolactucin being least potent."
Limitations: The EC50 values are read from Table 1. The body text states the potency ranking in words but does not repeat the numbers, so these figures are table-level verbatim information rather than sentence-level. Cell-based potency alone does not determine the intensity of the food as a whole, and because TAS2R43 is absent in a substantial share of people, this ranking does not apply uniformly across human populations.
Source: Overlapping activation pattern of bitter taste receptors affect sensory adaptation and food perception (Lang R; Lang T; Dunkel A; Ziegler F; Behrens M, 2022) · full text checked
Limits: Shows that TAS2R43 itself functions differently from person to person: carriers of the hT2R43 allele that encodes tryptophan at position 35 are highly sensitive to the bitterness of aloin and aristolochic acid, people without this allele cannot taste these compounds at low concentrations, and the same allele also raises sensitivity to saccharin. The authors also state that some people lack particular hT2R genes altogether.
Limitations: Lactucin was not among the tested compounds; this is not a problem specific to lactucin but concerns whether a TAS2R43-based potency ranking can be transferred to the whole population. Abstract-level extraction: allele frequency and the psychophysical n are not captured.
Source: Specific alleles of bitter receptor genes influence human sensitivity to the bitterness of aloin and saccharin (Pronin AN; Xu H; Tang H; Zhang L; Li Q; Li X, 2007) · abstract checked
Limits: Cell-based potency values for TAS2R43 cannot be transferred uniformly across human populations, because the receptor gene is deleted in a substantial number of people. TAS2R43 copy number ranges from 0 to 2, and the deletion allele reaches a global frequency of 0.33 among 946 subjects across 52 populations. The paper states that more than 20% of subjects in Europe lacked this gene.
Limitations: There is no sensory test using lactucin or chicory. This limitation is inferential, linking receptor genetics to the interpretation of the in vitro EC50.
Source: Copy Number Variation in TAS2R Bitter Taste Receptor Genes: Structure, Origin, and Population Genetics (Roudnitzky N; Risso D; Drayna D; Behrens M; Meyerhof W; Wooding SP, 2016) · full text checked
Show datacompound-lactucin —activates→ receptor-tas2r43
claim: clm-chicory-tas2r43 / type: mechanism / updated: 2026-08-30
caffeine remains bitter even for people lacking TAS2R43supported

Scope: The correspondence between the frequency of the gene deletion in human populations and perception

Note: An example that a single receptor cannot explain bitterness perception. "About 18-30%" is a review-level figure. Note that the primary data (946 people / 52 populations) give a deletion-allele frequency of 0.33, a different kind of quantity from "the proportion of individuals lacking the gene".

About 18-30% of the population lacks the TAS2R43 gene, yet caffeine's bitterness is perceived.
Limitations: Via a review. The primary source for the deletion frequency is not included.
Source: The Taste of Caffeine (Poole RL; Tordoff MG, 2017) · full text checked
Context: Gives the population-genetic basis underlying this claim from primary data rather than via a review: in 946 subjects from 52 populations worldwide, copy number for both TAS2R43 and TAS2R45 ranged from 0 to 2, and the 43delta and 45delta deletions occurred at high frequency worldwide (0.33 and 0.18). The TAS2R43 deletion spans 37.8 kb, including the entire coding region, and the paper states that in Europe more than 20% of subjects lacked this gene. No signal of natural selection was found, and the authors attribute this pattern to genetic drift.
Limitations: What this study measures is gene copy number, not caffeine perception, so the study itself does not show that caffeine remains bitter in the absence of TAS2R43. It also refines the figure carried over by the review: the reported quantity is a deletion-allele frequency of 0.33, which is not the same as the proportion of people lacking the gene; the paper gives a regional figure for Europe (more than 20%) rather than a single worldwide percentage. The 18-30% range recorded from Poole 2017 should therefore be treated as a review-level approximation.
Source: Copy Number Variation in TAS2R Bitter Taste Receptor Genes: Structure, Origin, and Population Genetics (Roudnitzky N; Risso D; Drayna D; Behrens M; Meyerhof W; Wooding SP, 2016) · full text checked
Show datacompound-caffeine —remains_bitter_despite_absence_of→ receptor-tas2r43
claim: clm-tas2r43-absent-still-bitter / type: mechanism / updated: 2026-08-30
saccharin activates TAS2R43supported

Scope: Layer: cell. Ca2+ imaging and luminescence assays in HEK293T cells with heterologous expression of TAS2R43.

"TAS2R43 is the receptor for the intrinsic aftertastes of saccharin and acesulfame K". "The results showed that (R)-(-)-carvone inhibited both TAS2R31 and TAS2R43 (Fig. 4A,B) but not TAS2R50 (Fig. 4C)." The condition in Fig. 4B was "2.5 mm saccharin Na in (B)".
Limitations: The IC50 value of (R)-(-)-carvone against TAS2R43 is not explicitly stated in the text and is shown only in figures (unverified). TAS2R43 response to acesulfame K was weak and outside the scope of this study.
Source: Menthol-like cooling compounds, including (R)-(-)-carvone, inhibit the human bitter taste receptors for saccharin and acesulfame K (Saito M; Misaka T, 2025) · full text checked
Show datacompound-saccharin —activates→ receptor-tas2r43
claim: clm-w71g1-tas2r43-saccharin-carvone-inhibition / type: mechanism / updated: 2026-09-07
caffeine activates TAS2R43preliminary

Scope: Layer: cell. Cell functional experiments using several human bitter taste receptors reported to be caffeine-sensitive (TAS2R7, TAS2R10, TAS2R14, TAS2R43, TAS2R46).

Note: Suess et al. 2018's full text was not reached because of a subscription restriction; confirmed from an OpenAlex abstract restoration (the paper's own abstract, not a secondary citation).

"Cell-based functional experiments, conducted with the human bitter taste receptors TAS2R7, TAS2R10, TAS2R14, TAS2R43, and TAS2R46 reported to be sensitive to caffeine, revealed (R)-citronellal to completely block caffeine-induced calcium signals in TAS2R43-expressing cells...Stimulation of TAS2R43-expressing cells with structurally different bitter agonists identified (R)-citronellal as a general allosteric inhibitor of TAS2R43."
Limitations: Full text not read; only the abstract-level description. Specific figures such as dose or IC50 are not given in the abstract.
Source: The Odorant (R)-Citronellal Attenuates Caffeine Bitterness by Inhibiting the Bitter Receptors TAS2R43 and TAS2R46 (Suess B; Brockhoff A; Meyerhof W; Hofmann T, 2018) · abstract checked
Show datacompound-caffeine —activates→ receptor-tas2r43
claim: clm-w71g1-tas2r43-caffeine-citronellal / type: mechanism / updated: 2026-09-07

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