1.3.4 Protein Interactions

Proteins interact with other molecules and proteins in cells to perform essential tasks. These interactions depend on the shape and chemical properties of each protein, allowing them to bind precisely to other molecules.

Types of Protein Interactions:

1. Enzyme-Substrate Interactions:

• Enzymes are proteins that speed up reactions by binding to specific substrates (reactants) at their active sites. This binding is very precise, like a lock-and-key, allowing enzymes to carry out specific chemical reactions.

2. Protein-Protein Interactions:

• Some proteins need to work together in pairs or groups, forming protein complexes. For example, haemoglobin consists of four protein chains working together to transport oxygen in the blood. Protein-protein interactions help proteins support each other or control each other's activity.

3. Protein-Ligand Interactions:

• Ligands are molecules that attach to specific proteins at binding sites. When ligands bind, they often change the protein's shape, affecting its function. A common example is insulin binding to its receptor on a cell, allowing glucose to enter the cell.

4. Signal Transduction:

• Proteins help cells communicate through signal transduction pathways. Proteins on cell surfaces interact with signalling molecules (like hormones) and pass messages into the cell, telling it how to respond. This process is crucial for cells to adapt to changes in their environment.

5. Structural Protein Interactions:

• Some proteins, like collagen and keratin, interact to form strong fibres, providing support and shape to body structures like skin, hair, and nails. These interactions make cells and tissues sturdy.