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mechanistic
Analysis v2
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The enzyme transglutaminase in human tissues has separate molecular pockets that bind Mg-GTP and Mg-ATP, allowing it to respond differently to each molecule based on their chemical structure.

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Mechanism

Synthesis from 1 study

How it works

This enzyme has two different spots that grab either Mg-GTP or Mg-ATP, even though they look almost identical. One spot turns off the enzyme’s glue-like function when Mg-GTP is present, while the other spot slows down the breakdown of Mg-GTP when Mg-ATP is around. This lets the enzyme switch...

Most probable mechanism

In Simple Terms

The enzyme has two separate pockets that grab either Mg-GTP or Mg-ATP, even though these molecules look almost the same. When Mg-GTP binds, it changes the enzyme’s shape and turns off its ability to glue proteins together. When Mg-ATP binds, it doesn’t change the shape but blocks Mg-GTP from being broken down, which keeps the GTP signal active. This lets the enzyme do two different jobs depending on which molecule is around.

Causal chain
1

Mg-GTP binds to a specific site on the enzyme, inducing a conformational change that reduces the catalytic efficiency of the transglutaminase active site.

Verified by multiple studies
which leads to
2

Mg-ATP binds to a distinct site on the enzyme with higher affinity than Mg-GTP, competitively inhibiting the hydrolysis of Mg-GTP without inducing the same conformational change.

Verified by multiple studies
which leads to
3

The conformational change triggered by Mg-GTP binding protects the enzyme from degradation and suppresses its protein-crosslinking function, while Mg-ATP binding modulates GTPase signaling without affecting structural stability.

Verified by multiple studies

Evidence from Studies

Supporting (1)

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Community contributions welcome

33

Regulation of Human Tissue Transglutaminase Function by Magnesium-Nucleotide Complexes

Case-Control Study
In Vitro
1998 Jan 16

Contradicting (0)

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No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

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Source Study

Regulation of Human Tissue Transglutaminase Function by Magnesium-Nucleotide Complexes

Score: 33
DOI: 10.1074/jbc.273.3.1776

Similar Assertions

Human tissue transglutaminase enzyme uses two magnesium-bound nucleotides, Mg-ATP and Mg-GTP, as substrates for hydrolysis, and Mg-ATP binds more tightly to the enzyme than Mg-GTP, suggesting differences in how the enzyme interacts with each molecule.

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In human tissue transglutaminase, the rates at which the enzyme breaks down GTP and ATP change in a coordinated way when the protein is shortened at its end, indicating that both molecules are processed by the same active site.

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88%

In human tissue transglutaminase, magnesium-bound ATP strongly blocks GTP breakdown at low concentrations, while magnesium-bound GTP only weakly blocks ATP breakdown even at high concentrations, showing that the two molecules affect each other's activity unequally.

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87%

Magnesium-bound guanine nucleotides (Mg-GTP, Mg-GDP, Mg-GMP) reduce the activity of human tissue transglutaminase at specific concentrations, while magnesium-bound adenine nucleotides do not, indicating that the enzyme is selectively regulated by guanine-based molecules.

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86%

When Mg-GTP binds to the enzyme tissue transglutaminase, it prevents the enzyme from being broken down by trypsin; Mg-ATP does not have this effect, suggesting that Mg-GTP changes the enzyme's shape in a way that makes it more stable.

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