Intracellular Protein Degradation Overview Quiz

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Which of the following is NOT a function of intracellular protein degradation?

Preventing the accumulation of abnormal proteins

Facilitating the synthesis of abnormal proteins (correct)

Regulating the turnover of proteins

Providing the cell with a constant supply of amino acids

What is the approximate half-life of 'normally' proteins?

200-300 hours

10-20 hours

100-200 hours (correct)

1-2 days

Which type of proteins have a shorter half-life?

Transcription factors

Special cases proteins

Enzymes that catalyze committed steps (correct)

Structural proteins

In which compartment does lysosomal protein degradation occur?

Lysosomes Signup and view all the answers

What is the pH of lysosomes where protein degradation occurs?

Acidic (pH=4.8) Signup and view all the answers

Which type of proteins are primarily degraded by the cytosol-ubiquitin dependent proteasome system?

Long-lived proteins Signup and view all the answers

What is the half-life of Acetyl CoA carboxylase in a fasted state?

18 Signup and view all the answers

Which tissue has the shortest half-life for Lactic Acid Dehydrogenase?

Heart Signup and view all the answers

Which organelles contain digestive enzymes such as lipases, nucleases, and proteases?

Lysosomes Signup and view all the answers

What percentage of protein degradation occurs in the acidified compartment of lysosomes?

10-20% Signup and view all the answers

What is the main process by which vesicles are formed to engulf small amounts of cytoplasm or specific organelles?

Autophagosomes formation Signup and view all the answers

Which nutritional state results in a longer half-life for Acetyl CoA carboxylase?

Fed state Signup and view all the answers

What is responsible for the breakdown of most short-lived proteins in human cells?

Proteosomal degradation Signup and view all the answers

Which protein is tagged by the covalent attachment of ubiquitin for degradation?

Substrate Signup and view all the answers

What is the function of the 19S regulatory particle in the 26S proteasome?

Recognition and binding of polyubiquitinated proteins Signup and view all the answers

What is responsible for the catalysis of the transfer of ubiquitin from E2 to a lysine amino group of the condemned protein?

Enzyme 3 (E3) Signup and view all the answers

What is recycled in the process of proteasomal degradation?

Ubiquitin Signup and view all the answers

Which component is important for the translocation of unfolded proteins into the central core of the proteasome?

19S regulatory particle Signup and view all the answers

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

4 Signup and view all the answers

What is the function of Deubiquitinating enzymes (DUBs)?

Reverse the degradation effects by cleaving the peptide or isopeptide bond between ubiquitin and its substrate protein Signup and view all the answers

Which enzyme family contains relatively small proteins (< 40-kDa)?

UCH (Ubiquitin Carboxyl-terminal Hydrolases) Signup and view all the answers

What is the role of UBP (UBiquitin-specific Processing proteases) gene family?

Reverse the degradation effects by cleaving the peptide or isopeptide bond between ubiquitin and its substrate protein. Signup and view all the answers

What is structurally formed from 7 alpha subunits and 7 beta subunits?

Proteasome 20S core Signup and view all the answers

What is involved in regulation of DNA repair, transcription, and endocytosis?

Ubiquitin Signup and view all the answers

Which organelles contain digestive enzymes such as lipases, nucleases, and proteases?

Lysosomes Signup and view all the answers

What is the pH of lysosomes where protein degradation occurs?

pH=4.8 Signup and view all the answers

What is the main process by which vesicles are formed to engulf small amounts of cytoplasm or specific organelles?

Autophagy Signup and view all the answers

Which nutritional state results in a longer half-life for Acetyl CoA carboxylase?

Fed state Signup and view all the answers

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

Ten ubiquitin molecules Signup and view all the answers

Which component is responsible for the recognition and binding of polyubiquitinated proteins, removal of ubiquitin, unfolding the protein substrate, and translocation into the central core of the proteasome?

19S regulatory particle Signup and view all the answers

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

Four ubiquitin molecules Signup and view all the answers

What is the function of Deubiquitinating enzymes (DUBs)?

Reversing the degradation effects by cleaving the peptide or isopeptide bond between ubiquitin and its substrate protein Signup and view all the answers

What is the role of UBP (UBiquitin-specific Processing proteases) gene family?

Regulating protein degradation by cleaving ubiquitin from its substrate Signup and view all the answers

What is responsible for the breakdown of most short-lived proteins in human cells?

Proteosomal degradation pathway Signup and view all the answers

Explain the process of protein degradation through ubiquitination and proteasomal degradation. What are the key enzymes and components involved in this process?

Proteins destined for degradation are tagged by the covalent attachment of ubiquitin, followed by degradation by the proteasome. This ubiquitination process involves E1 (ubiquitin activating enzyme), E2 (ubiquitin conjugating enzyme), and E3 (ubiquitin ligase) enzymes. The 26S proteasome, consisting of a 20S core and 19S regulatory particle, is responsible for recognizing and binding polyubiquitinated proteins, removing ubiquitin, unfolding the protein substrate, and translocating it into the central core for degradation. Signup and view all the answers

What is the role of deubiquitinating enzymes (DUBs) in the protein degradation process?

Deubiquitinating enzymes (DUBs) can reverse the degradation effects by cleaving the peptide or isopeptide bond between ubiquitin and its substrate protein. They play a role in regulating the ubiquitination process and can affect protein function. Signup and view all the answers

Describe the structural composition of the 26S proteasome. What are the functions of its core and regulatory particle?

The 26S proteasome consists of a central core (20S) and 19S regulatory particles at either end. The 20S core is formed of 4 rings: the outer rings are formed from 7 alpha subunits and the inner ring is formed from 7 beta subunits. The 19S regulatory particle is important for recognizing and binding polyubiquitinated proteins, removing ubiquitin, unfolding the protein substrate, and translocating it into the central core for degradation. Signup and view all the answers

How is ubiquitin recycled in the process of proteasomal degradation?

Ubiquitin is recycled, not cleaved, during the proteasomal degradation process. Signup and view all the answers

What is the minimum number of ubiquitin molecules required on a target protein for efficient degradation?

A minimum of four ubiquitin molecules on the target protein are critical for efficient degradation of the protein. Signup and view all the answers

Intracellular Protein Degradation Overview Quiz

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Questions and Answers

Which of the following is NOT a function of intracellular protein degradation?

What is the approximate half-life of 'normally' proteins?

Which type of proteins have a shorter half-life?

In which compartment does lysosomal protein degradation occur?

What is the pH of lysosomes where protein degradation occurs?

Which type of proteins are primarily degraded by the cytosol-ubiquitin dependent proteasome system?

What is the half-life of Acetyl CoA carboxylase in a fasted state?

Which tissue has the shortest half-life for Lactic Acid Dehydrogenase?

Which organelles contain digestive enzymes such as lipases, nucleases, and proteases?

What percentage of protein degradation occurs in the acidified compartment of lysosomes?

What is the main process by which vesicles are formed to engulf small amounts of cytoplasm or specific organelles?

Which nutritional state results in a longer half-life for Acetyl CoA carboxylase?

What is responsible for the breakdown of most short-lived proteins in human cells?

Which protein is tagged by the covalent attachment of ubiquitin for degradation?

What is the function of the 19S regulatory particle in the 26S proteasome?

What is responsible for the catalysis of the transfer of ubiquitin from E2 to a lysine amino group of the condemned protein?

What is recycled in the process of proteasomal degradation?

Which component is important for the translocation of unfolded proteins into the central core of the proteasome?

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

What is the function of Deubiquitinating enzymes (DUBs)?

Which enzyme family contains relatively small proteins (< 40-kDa)?

What is the role of UBP (UBiquitin-specific Processing proteases) gene family?

What is structurally formed from 7 alpha subunits and 7 beta subunits?

What is involved in regulation of DNA repair, transcription, and endocytosis?

Which organelles contain digestive enzymes such as lipases, nucleases, and proteases?

What is the pH of lysosomes where protein degradation occurs?

What is the main process by which vesicles are formed to engulf small amounts of cytoplasm or specific organelles?

Which nutritional state results in a longer half-life for Acetyl CoA carboxylase?

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

Which component is responsible for the recognition and binding of polyubiquitinated proteins, removal of ubiquitin, unfolding the protein substrate, and translocation into the central core of the proteasome?

What is the critical number of ubiquitin molecules on a target protein for efficient degradation?

What is the function of Deubiquitinating enzymes (DUBs)?

What is the role of UBP (UBiquitin-specific Processing proteases) gene family?

What is responsible for the breakdown of most short-lived proteins in human cells?

Explain the process of protein degradation through ubiquitination and proteasomal degradation. What are the key enzymes and components involved in this process?

What is the role of deubiquitinating enzymes (DUBs) in the protein degradation process?

Describe the structural composition of the 26S proteasome. What are the functions of its core and regulatory particle?

How is ubiquitin recycled in the process of proteasomal degradation?

What is the minimum number of ubiquitin molecules required on a target protein for efficient degradation?

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