Question:
This molecule attaches to a protein before its destruction?
This molecule attaches to a protein before its destruction?
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Which small protein tags targets for the proteasome in an ATP-dependent way?
Updated On: Jun 24, 2026
- Ubiquitin
- RNAse F
- Zymase
- Chaperone
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The Correct Option is A
Solution and Explanation
Step 1: Eukaryotes have two main protein degradation pathways. One uses lysosomal proteases and is ATP independent; the other uses ubiquitin and is ATP dependent.
Step 2: In the ubiquitin pathway, the small protein ubiquitin is covalently tagged onto target proteins. A chain of ubiquitin molecules marks the protein for delivery to the proteasome, where it is degraded.
Step 3: This system is especially important for disposing of misfolded proteins and short-lived regulatory enzymes. RNase F and zymase are not protein-degradation tags, and a chaperone assists folding rather than marking for destruction. Hence the molecule attached before destruction is ubiquitin.
Step 2: In the ubiquitin pathway, the small protein ubiquitin is covalently tagged onto target proteins. A chain of ubiquitin molecules marks the protein for delivery to the proteasome, where it is degraded.
Step 3: This system is especially important for disposing of misfolded proteins and short-lived regulatory enzymes. RNase F and zymase are not protein-degradation tags, and a chaperone assists folding rather than marking for destruction. Hence the molecule attached before destruction is ubiquitin.
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