09a: Protein Trafficking Flashcards
T/F: synthesis of all proteins begins on cytoplasmic ribosomes.
True
Proteins translated on cytoplasmic ribosomes are targeted to:
- Cytoplasm
- Mitochondria
- Nucleus
Proteins translated on RER ribosomes are targeted to:
- Cell membrane
- Lysosomes
- Cell secretion
What’s the power house of protein synthesis?
RER
Information that determines site of a protein’s localization is found in its (primary/secondary/tertiary) structure.
Primary
Cytoplasmic protein have which signal?
No signal
Mitochondrial protein have which signal?
Pre-sequence with amiphipathic character (hydrophobic and positively-charged AA) on N-terminus
Nuclear proteins have which signal?
Lys-Lys-Lys-Arg-Lys
Membrane proteins have which signal?
Core of hydrophobic AA near N terminus
Secretory proteins have which signal?
Core of hydrophobic AA near N terminus
Lysosomal proteins have which signal?
Mannose-6-P
SRP stands for (X) and is similar in composition to (Y).
X = Signal Recognition Particle Y = snRNPs (has RNA and protein components)
What’s the function of SRPs?
Bind signal peptide on secretory, membrane, lysosomal proteins that have begun translation on cytoplasmic ribosomes
Once SRP binds (X), translation is paused until:
X = signal peptide
SRP binds its receptor on ER membrane
T/F: Ribosomes on ER are fixed on the membrane.
False - when SRP binds signal peptide, it carries ribosome to ER to continue translation of the protein