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...
Mechanism
Synthesis from 1 study
A part of this protein normally blocks its own ability to break down two similar molecules, GTP and ATP. When that block is removed, both molecules get broken down faster — and at exactly the same rate — proving the protein uses one single tool to handle both.
Most probable mechanism
A part of the protein blocks its own ability to break down GTP and ATP. When that blocking part is removed, the protein can break down both molecules much faster, and it does so at the same rate for both — meaning it uses the same internal tool to handle both GTP and ATP.
The C-terminal region of tissue transglutaminase physically obstructs access to a catalytic site located in the N-terminal domain.
Removal of the C-terminal region exposes the catalytic site, allowing GTP and ATP to bind and be hydrolyzed with increased catalytic turnover.
The exposed catalytic site hydrolyzes GTP and ATP with parallel changes in reaction rate (Kcat), indicating both nucleotides are processed by the same active site.
The catalytic efficiency for both nucleotides increases proportionally across truncation mutants, while substrate binding affinity (Km) remains unchanged, confirming that the mechanism affects catalysis, not binding.
Evidence from Studies
Supporting (1)
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C-terminal Deletion of Human Tissue Transglutaminase Enhances Magnesium-dependent GTP/ATPase Activity*
Contradicting (0)
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