Chapter 10.5: Proteins Are Sometimes Modified after Translation

Flashcards from Chapter 10.5 of Principles of Life, 3rd Edition.

Signal sequences

A sequence of amino acids that indicates the required location of the polypeptide after translation

• For use in the endomembrane system, binding this to a recognizer halts translation until bound to the rough endoplasmic reticulum (RER) for protein storage while this is cleaved

• For use in other organelles, another protein binds to this for direction

Proteolysis

A post-translational modification of a protein involving the cutting of a polypeptide chain by enzymes called proteases

• Some proteins can be produced in this way before folding

• Also seen with the removal of signal sequences or the initiator methionine

Glycosylation

A post-translational modification of a protein involving the addition of carbohydrates to form stabilized glycoproteins

• These can aid in organelle and cell signalling, like on the surface of red blood cells

Photophosphorylation

A post-translational modification of a protein involving the addition of phosphate groups, catalyzed by protein kinases

• These can change the conformation of the protein, exposing an enzyme’s active site or binding site for another protein

• Is often reversible for protein regulation