Podcast
Questions and Answers
What role does the receptor protein play in protein transport?
What role does the receptor protein play in protein transport?
Which type of protein targeting signal is used for visualizing the endoplasmic reticulum?
Which type of protein targeting signal is used for visualizing the endoplasmic reticulum?
What must happen for the receptor-cargo complex to be successfully imported into the compartment?
What must happen for the receptor-cargo complex to be successfully imported into the compartment?
What type of energy is primarily involved in the transport of protein cargo?
What type of energy is primarily involved in the transport of protein cargo?
Signup and view all the answers
What distinguishes the nuclear pore complexes in the nuclear envelope?
What distinguishes the nuclear pore complexes in the nuclear envelope?
Signup and view all the answers
Why are protein targeting pathways essential for cellular function?
Why are protein targeting pathways essential for cellular function?
Signup and view all the answers
What is the role of a protein targeting sequence?
What is the role of a protein targeting sequence?
Signup and view all the answers
What is a major limitation in the transport of proteins between cellular compartments?
What is a major limitation in the transport of proteins between cellular compartments?
Signup and view all the answers
Which cellular structures synthesize a limited number of proteins independently?
Which cellular structures synthesize a limited number of proteins independently?
Signup and view all the answers
What machinery is primarily involved in the protein transport process?
What machinery is primarily involved in the protein transport process?
Signup and view all the answers
Study Notes
Cell Biology: Protein Targeting
- Protein Targeting Pathways: Proteins require signals, receptors, and transport complexes to be directed to specific organelles.
- Classical Nuclear Localization Signal (NLS): A stretch of basic amino acids (lysine and arginine) within a protein sequence.
- Bipartite/Mono-partite NLS: A type of NLS; bipartite consists of two short stretches of basic amino acids, whereas monobartite is a single stretch.
- NLS function: The NLS guides proteins towards the nucleus.
Protein Targeting Summary
- Targeting Signal: The specific amino acid sequence directing a protein to a particular compartment.
- Receptor: A protein that recognizes and binds the targeting signal.
- Transport Complex: A protein complex that transports the cargo protein across membranes or within the cell.
- Energy Requirement: Often GTP hydrolysis powers these processes.
- Stage of Protein Delivery: Protein delivery can occur co-translationally (during protein synthesis) or post-translationally (after synthesis).
- Protein State (during Transport): The folded state of proteins during transfer is important. Some proteins are folded before moving and some after.
- Examples of targeting signals and receptors: Importins (import) and exportins (export); and karyopherins.
Nuclear Pore Complex (NPC)
- Structure: The NPC comprises ~500-100 different nucleoporins (Nups) that form a channel across the nuclear envelope regulating transport.
- Function: The complex acts as a molecular sieve selectively allowing the passage of molecules into and out of the nucleus.
- Molecular Sieve: Limits passage of macromolecules based on size. Smaller molecules can pass freely.
- FG-Nups: Fibronectin-like repeats assist in transport regulation.
- Nuclear Transport Receptors (e.g., Importins and Exportins): these recognize targeting signals and assist in transport.
- The Ran-GTP cycle: Ran proteins facilitate energy-dependent import/export between the nucleus and cytoplasm.
Targeting to the Nucleolus
- Nucleolus Structure: One of the nucleus's components involved in ribosome synthesis.
- Nucleolus Function: Important for ribosome production.
Additional Notes
- Protein Localization Signal: A specific sequence within a protein molecule directing it to a particular location.
- Diffusion: The unassisted movement of small molecules between compartments.
- Protein Folding: The process by which a protein folds into its functional three-dimensional shape.
- Cytoplasm-to-Nucleus Transport: This transport is facilitated by protein import receptors, targeting sequences, the nuclear pore complex (NPC), and the Ran-GTP cycle.
- Protein Translation: The process of synthesizing proteins from mRNA.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz explores the intricate pathways of protein targeting within cells, focusing on signals, receptors, and transport mechanisms. Understand the roles of nuclear localization signals (NLS) and their importance in directing proteins to the nucleus. Delve into the specifics of bipartite and monobartite NLS while considering the energy requirements of protein delivery.
