BIO230 Lecture 1-9 & 1-10: Protein Sorting

Practice flashcards covering the key concepts of protein sorting and regulation of genome expression discussed in the lecture.

What are the main destinations for protein sorting in eukaryotic cells?

The proteins are sorted to the nucleus, mitochondria, chloroplasts, and peroxisomes.

What are sorting signals and receptors in protein sorting?

Sorting signals direct proteins to their correct location, while sorting receptors help recognize and bind these proteins for transport.

What is the role of Nuclear Pore Complexes?

Nuclear Pore Complexes perforate the nuclear envelope and facilitate the selective transport of molecules between the nucleus and cytosol.

What is the function of Ran GTPase in nuclear import and export?

Ran GTPase imposes directionality on nuclear transport, facilitating the import and export of proteins.

Describe the post-translational process of protein sorting in mitochondria.

Proteins are fully synthesized in the cytosol before sorting, and they are imported into mitochondria as unfolded polypeptide chains.

How do proteins enter the nucleus?

Proteins enter the nucleus through nuclear import receptors that recognize the Nuclear Localization Signal (NLS) and bind to the Nuclear Pore Complex.

What is the difference between nuclear import and nuclear export?

Nuclear import transports proteins from the cytosol to the nucleus, while nuclear export moves proteins from the nucleus to the cytosol.

What role does the Signal Recognition Particle (SRP) play in protein sorting to the ER?

SRP directs the ER signal sequence to a specific receptor at the ER membrane during co-translational translocation.

What is the significance of hydrophobic segments in transmembrane proteins?

Hydrophobic segments are recognized as signal sequences that determine the orientation and insertion of transmembrane proteins.

What type of proteins require GPI anchors?

GPI-anchored proteins are targeted to the ER and end up on the extracellular surface after being transferred to a GPI anchor.