During their life cycle proteins undergo many types of conformational changes.  The first type of conformational change is the process of protein folding.  The polypeptide must fold into its active three-dimensional structure before it is degraded by cellular proteases or aggregates. In fact this process is so important that organisms have developed systems such as Chaperonins that consume energy to assist in the folding process. Once the protein has obtained its proper three-dimensional structure it may undergo further structural changes that are associated with its function. Many enzymes and ligand-binding proteins must undergo large conformational changes during their function. The activity of a protein can be modulated by allosteric interactions with other molecules. These interactions result in a dynamic structural change that changes the protein's activity. Finally, most proteins only survive a short time in the cell without becoming damaged.  Damage often will change the structure of the protein and allow proteases to degrade it allowing the cycle to begin anew.  If the degradation process is faulty then aggregation can occur.  Thus, during their life cycle proteins can undergo five basic classes of conformational change.

• Folding
• Activity
• Regulation
• Degradation
• Aggregation

Defects in these processes can result in diseases.