How Mutations in Amino Acid Sequences Affect Protein Function
Proteins are made up of chains of amino acids arranged in a specific sequence. This sequence determines how the protein folds into its three-dimensional shape, which in turn decides its function. When a mutation changes one or more amino acids in that sequence, it can affect the protein’s structure and function in different ways.
- Change in Protein Structure:
A small change in the amino acid sequence can alter how the protein folds. Since the shape of a protein is crucial for its activity, an incorrect fold can make it less effective or completely nonfunctional. - Loss of Function:
Some mutations cause the protein to lose its normal activity. For example, if an enzyme’s active site is changed, it may no longer bind to its substrate, stopping the chemical reaction it normally catalyzes. - Gain of Abnormal Function:
In some cases, mutations create a protein that works in a harmful or abnormal way. For example, certain mutations in cell-growth proteins can cause uncontrolled cell division, leading to cancer. - Misfolding and Aggregation:
Mutations can cause proteins to fold incorrectly and stick together inside cells. These clumps can damage cells and tissues, as seen in diseases like Alzheimer’s and Parkinson’s. - No Effect (Silent Mutations):
Not all mutations cause problems. Sometimes, the new amino acid is similar to the original, or the change occurs in a part of the protein that doesn’t affect its function.
In short:
Mutations in amino acid sequences can change the shape, stability, or activity of a protein. Some changes are harmless, but others can lead to serious diseases or loss of normal cell functions.