Related Experiment Video
Updated: May 21, 2026
07:00
A Method to Study the C924T Polymorphism of the Thromboxane A2 Receptor Gene
Published on: April 1, 2019
Functional analysis of human thromboxane synthase polymorphic variants.
Chung-Ying K Chen1, Elizabeth M Poole, Cornelia M Ulrich
1Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
Pharmacogenetics and Genomics
|June 28, 2012
Summary
Genetic variants in Thromboxane A synthase (TXAS) were studied. The L357V variant showed reduced activity, potentially decreasing thromboxane A2 (TXA2) generation and altering signaling pathways.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacogenomics
Background:
- Thromboxane A synthase (TXAS) synthesizes thromboxane A2 (TXA2), a key regulator of blood vessel constriction and platelet aggregation.
- Genetic variations in TXAS can impact enzyme activity and TXA2 production, influencing cardiovascular health.
Purpose of the Study:
- To investigate the functional impact of specific TXAS gene variants (K258E, L357V, Q417E, E450K, T451N) on enzyme activity.
- To characterize the kinetic properties of TXAS variants in vitro.
Main Methods:
- Recombinant wild-type and variant TXAS proteins were expressed in bacteria and purified.
- Enzyme kinetics were assessed by measuring TXAS-catalyzed isomerization of prostaglandin H2 (PGH2) to TXA2 and fragmentation to 12-hydroxyheptadecatrienoic acid.
Main Results:
- All TXAS variants exhibited both isomerization and fragmentation activities.
- The L357V variant displayed the most significant kinetic alterations, with a Vmax/Km ratio of 27% compared to wild-type TXAS.
- Variant Km values ranged from 27–52 µmol/l PGH2, and Vmax values ranged from 18–40 U/mg.
Conclusions:
- The L357V variant's reduced catalytic efficiency suggests diminished TXA2 generation in vivo.
- This finding implies a potential for attenuated thromboxane pathway signaling in individuals with the L357V variant.
Related Concept Videos
01:11Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Genetic polymorphisms in drug targets have emerged as critical determinants of interindividual variability in drug response and toxicity. Pharmacogenomic investigations increasingly focus on identifying these variations to personalize and optimize therapeutic interventions. A drug target may be a receptor, enzyme, or signaling protein involved in pharmacologic responses or disease-related pathways. While early pharmacogenetic studies focused primarily on drug metabolism, current research...
01:29Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu
Genetic variations significantly influence drug response through pharmacokinetics, receptor interactions, and biologic milieu modifications. Pharmacokinetic alterations impact drug metabolism and clearance, affecting efficacy and toxicity. Variants in drug-metabolizing enzymes, such as CYP2C9 and CYP2C19, alter drug activation and elimination. For example, CYP2C9 loss-of-function variants require lower warfarin doses to prevent excessive bleeding, while CYP2C19 variants reduce clopidogrel...
01:48ATP Synthase: Mechanism
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
01:28Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
Cytochrome P450 (CYP450) enzymes are a superfamily of heme-containing monooxygenases that play a pivotal role in Phase I drug metabolism by catalyzing oxidation and reduction reactions.These enzymes transform lipophilic xenobiotics into more hydrophilic metabolites, facilitating subsequent Phase II conjugation and eventual excretion. The CYP450 family is classified into families (e.g., CYP1–CYP3) and subfamilies (e.g., CYP2A, CYP2C), based on amino acid sequence homology.CYP450 isoenzymes,...
01:18ATP Synthase: Structure
ATP synthase or ATPase is among the most conserved proteins found in bacteria, mammals, and plants. This enzyme can catalyze a forward reaction in response to the electrochemical gradient, producing ATP from ADP and inorganic phosphate. ATP synthase can also work in a reverse direction by hydrolyzing ATP and generating an electrochemical gradient. Different forms of ATP synthases have evolved special features to meet the specific demands of the cell. Based on their specific feature, ATP...
01:27Principles of Pharmacogenetics: Types of Genetic Variants
The human genome is over 99.9% identical between individuals, yet genetic differences exist at millions of bases. The human genome contains approximately 3 million variant positions per individual, many of which are heterozygous, contributing to genetic diversity and individual traits. Genetic variations include single-nucleotide polymorphisms (SNPs), insertions, deletions, and copy number variations (CNVs).SNPs, the most common variation, involve single-base changes in DNA. These can be...