4-Cell Structure and Function II

What is a sorting signal?

A sorting signal is a short sequence of amino acids within a protein that directs the protein to its correct location.

What is the example of a sorting signal that we learned in class?

The ER signal sequence

What type of sorting occurs after a protein has been produced?

Post-Translational Sorting

What type of sorting occurs while the protein is being produced?

Cotranslational Sorting

What type of sorting do proteins directed to the ER undergo?

Cotranslational

What types of proteins undergo post-translational sorting?

Proteins located in the:

nucleus

mitochondria

chloroplasts

peroxisomes

Other than ER proteins, what other types of proteins are cotranslationally sorted to the ER?

Golgi proteins

Lysosome proteins

Vacuole proteins

Plasma membrane proteins

Secreted proteins.

How do proteins sorted to the ER get to the golgi apparatus?

through a vesicle

How do proteins get from the golgi apparatus to their final destination?

through a vesicle

Place the following steps of cotranslational sorting to the ER in the correct order:

1. SRP binds to the SRP Receptor in the ER memrbane

2. SRP is released, translation resumes, and the protein is synthesized into the ER lumen

3. The ER signal sequence emerges from the ribosome

4. SRP binds to the ER signal sequence and pauses translation

1. The ER signal sequence emerges from the ribosome

2. SRP binds to the ER signal sequence and pauses translation

3. SRP binds to the SRP receptor in the ER membrane

4. SRP is released, translation resumes, and the protein is synthesized into the ER lumen