PTC, or "taste-cell activating gene," is a gene that is responsible for encoding a protein called PTC taste receptor. The PTC gene is located on chromosome 7 in humans and has been identified as a key player in the ability to taste the chemical compound phenylthiocarbamide (PTC). This chemical has a bitter taste to most people, but some individuals are unable to taste it due to a genetic variation in the PTC gene.
The PTC gene is part of a family of genes known as the TAS2R (taste receptor type 2) family. These genes encode proteins that are found on the surface of taste cells in the tongue and are responsible for detecting the taste of different chemicals in the mouth. When a chemical binds to a taste receptor protein, it activates the taste cell and sends a signal to the brain, allowing us to perceive the taste of that chemical.
The PTC gene is one of the most studied genes in the TAS2R family due to its role in taste perception. Many studies have been conducted to understand how variations in the PTC gene affect an individual's ability to taste PTC. It has been found that individuals with a specific variation in the PTC gene are unable to taste PTC, while those without this variation can taste it. This variation is thought to be caused by a single base pair change in the DNA sequence of the gene, resulting in a slightly different amino acid sequence in the PTC taste receptor protein.
In addition to its role in taste perception, the PTC gene has also been linked to other physiological processes. For example, some studies have suggested that variations in the PTC gene may be associated with an increased risk of certain types of cancer, such as breast and ovarian cancer. Other studies have also suggested that the PTC gene may play a role in the development of obesity and other metabolic disorders.
Overall, the PTC gene is an important gene that plays a key role in taste perception and may also be involved in other physiological processes. Further research is needed to fully understand the function of the PTC gene and how variations in this gene may impact an individual's health and well-being.
Genetic study of phenylthiocarbamide (PTC) taste perception among six human populations of Jammu and Kashmir (India)
When you transfer some of it to your PCR tube, be sure not to transfer any of the Chelex-containing pellet; it will interfere with PCR. The technique of Harris and Kalmus 1950 for threshold measurement has been widely used, sometimes with small modifications. Each subject had different thresholds at different times; in the most extreme case, one person sometimes had a threshold of 0. Make enough master mix for the number of PCRs you're doing, plus one extra. Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide. SNPs Present in Tasters vs Non-Tasters for PTC Nucleotide position bp Nucleotide Change Codon Change Amino Acid Change phenotype Non-Taster Taster Non-taster Taster Non-taster Taster 145 G C GCA CCA Alanine Proline 785 T C G TT G CT Valine Alanine 886 A G ATC GTC Isoleucine Valine Before you figure out your tasting ability, lets first understand the genetics of the alleles. One had a PTC threshold right on the borderline between taster and non-taster.
PTC Laboratories
At the conclusion of this experiment, was found that the sour, salty, sweet and bitter nature between the ages were essentially same. These sensory tastes are varied in individual of receptors that bind to the molecules that result in our perception of these sensations. Your DNA is now ready to use in PCR. Acts as a dependence receptor; in the presence of the ligand GDNF in somatotrophs within pituitary , promotes survival and down regulates growth hormone GH production, but triggers apoptosis in absence of GDNF. The prognostic significance of these mutations have been hotly debated in the field, however, data suggests that some RET mutation may confer drug resistence.
PTC Taster PCR
Both alleles taster and non-taster produce PCR products of identical size, but the taster allele contains a restriction site for a particular restriction enzyme SatI , while the nontaster allele doesn't. Studies indicate that individuals with the "strong tasters" PTC gene variant were less likely to be smokers. The primer sequences for this experiment are described on the Here is the sequence of the entire 303-bp base pairs, or nucleotide pairs PCR product shown above: AACT GGCAGAATAA AGATCTCAAT TTATTTTATT CCTTTCTCTT CTGCTATCTG TGGTCTGTGC CTCCTTTCCT ATTGTTTCTG GTTTCTTCTG GGATGCTGAC TGTCTCCCTG GGAAGGCACA TGAGGACAAT GAAGGTCTAT ACCAGAAACT CTCGTGACCC CAGCCTGGAG GCCCACATTA AAGCCCTCAA GTCTCTTGTC TCCTTTTTCT GCTTCTTTGT GATATCATCC TGT GTTGCCT TCATCTCTGT GCCCCTACTG ATTCTGTGGC GCGAC AAAAT AGGGGTGATG GTTTGTGTT The primer binding regions are highlighted in orange, with a SatI restriction site described below in pink. Journal of Nutrigenetics and Nutrigenomics 2: 251-256. PCR Calculations for PCR Before you can set up your PCR reactions, you will need to prepare a master mix also called a cocktail that contains all the PCR ingredients except the template DNA, which will be different for each reaction. This gene encodes a taste receptor protein; one common TAS2R38 allele encodes a receptor protein that responds strongly to PTC, while the other common allele encodes a receptor protein that doesn't respond.
PTC tasting
And an individual's sensitivity may change over time. Restriction digest You'll need to digest your PCR products with the restriction enzyme SatI so you can tell the difference between the "taster" and "nontaster" alleles. Each receptor can interact with several compounds, allowing people to taste a wide variety of bitter substances. For most of the myths in this series, I had to dig deep to find every obscure scrap of information, but for PTC, I am just skimming the surface. In other words, the enzyme will only cut the DNA at these sequences. Procedure Place a PTC or PROP strip on your tongue and leave it for 5 seconds.
PTC Genotyping
Kalmus and Trotter 1962 retested 110 people after about 15 years and found an increase in the average threshold; two people changed between taster and non-taster. To understand how the genes are inherited, examine table 2 below where the potential offspring of two heterozygous parents are analyzed. Fox insisted that it was tasteless; to settle the disagreement, he had other colleagues taste the PTC and discovered that it had a strong bitter taste for some people, while others found it tasteless. Explain how the polymorphisms are different, and how we use different approaches to identify each person's genotype in these two experiments. Proceedings of the National Academy of Sciences of the USA 21: 78-83.
