Protein sorting

Protein Sorting

Learning Goal:Understand the role of the endomembrane system in protein sorting.

•Explain the mechanism of protein sorting and its role in protein localization inside or outside the cell.

Protein sorting sends proteins to their target destination so that they can perform their function. 

•Describe the role of the components of the endomembrane system as they relate to cellular function.

-The nuclear envelope defines the boundary of the nucleus

-Lysosomes degrade macromolecules

-The endoplasmic reticulum is involved in lipid synthesis

-Rough ER synthesizes proteins

-Golgi Apparatus modifies and sorts proteins/lipids

-The nucleus houses the genome and is the site of RNA synthesis

-Vesicles transport substances within a cell

•Recognize that not all proteins are translated on the RER.

-Some are translated by free-floating ribosomes

•Evaluate the consequences of adding a drug or inducing a mutation that alters protein trafficking through the

endomembrane system.

Proteins cannot get to where they need to be to function, and likely stay in cytosol

•Determine where a protein was translated based on its function and/or cellular location.

Proteins synthesized on free-floating ribosomes are proteins for the chloroplast, mitochondria, or nucleus. 

They contain a signal sequence so that they can be recognized and proteins without a SS remain in cytosol. 

Proteins synthesized in the rough ER end up as transmembrane proteins or ER lumen, Golgi lumen, lysosome

lumen, or secretion. In other words, they are part of the Endomembrane system.