28 Questions
What is the primary reason for the dietary requirement of protein?
To compensate for the body's inability to synthesize certain amino acids
What is the net result of continuous protein synthesis and breakdown in the body?
Maintenance of optimally functioning proteins
What type of bond is formed between the first ubiquitin and the protein substrate in the ubiquitin/proteasome system?
Isopeptide bond
What is the primary function of the ubiquitin/proteasome system?
To target cytosolic and nuclear proteins for rapid proteolysis
What is the term for the continual renewal or replacement of protein in the body?
Protein turnover
What is the name of the network that regulates protein synthesis and degradation?
The proteostasis network
What is the primary function of the proteasome in the ubiquitin-proteasome system?
To recognize and degrade polyubiquinated proteins
What is the typical number of ubiquitin molecules required to target a protein for destruction?
4 or more
What is the energy requirement for the ubiquitin-proteasome system?
ATP
What is the primary function of the ubiquitin-like fold in ubiquitin?
To adopt a compact globular structure
What is the result of ubiquitin serving as its own substrate?
Polyubiquitylation
What is the first stage in the ubiquitin-proteasome system?
Ubiquitin activation
What energy source fuels the ubiquitination reaction?
Hydrolysis of ATP
Which enzyme is responsible for transferring Ub to a cysteine residue?
E2 conjugating enzyme
What is the function of the 19S regulatory particle (RP) in the proteasome?
It recognizes ubiquitylated client proteins and unfolds them
Which type of autophagy degrades soluble or unfoldable proteins in a molecule-by-molecule fashion?
Chaperone-mediated autophagy
What is the criterion for a protein to be a putative CMA substrate?
Presence of a peptide sequence related to the KFERQ motif
What is the term for the equilibrium between protein intake and losses?
Nitrogen balance
What is the term for a state where nitrogen intake exceeds nitrogen output?
Anabolic state
What is the optimal daily nitrogen balance for anabolism?
2-4g
Which disease is caused by maternal deficiency of the E6-AP ubiquitin E3 ligase (UBE3A)?
Angelman syndrome
What is the term for the process by which cytoplasmic contents are degraded within the lysosome/vacuole?
Autophagy
What is the primary component of nitrogen output?
Urine urea nitrogen
What is the recommended daily protein intake for a 72-kg man?
58 g protein/day
What is the constant used to account for nitrogen losses from the skin and feces?
4
What is the term for the type of malnutrition caused by inadequate intake of both protein and energy?
Marasmus
What is the purpose of dividing the daily protein intake by 6.25?
To calculate the total nitrogen intake
What is the term for the condition that results from a negative nitrogen balance?
Protein-Energy Malnutrition
Test your knowledge of nitrogen metabolism, protein turnover, and the essential amino acids required for dietary protein synthesis. Learn about the importance of protein turnover and the role of amino acids in the body.
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