The Protein Data Bank (PDB) is the essential global archive for 3D structural data of proteins and other biological molecules, providing the atomic-level "what does it look like?" to complement sequence data. By revealing the precise shape of proteins, the PDB is fundamental for understanding how proteins function and malfunction in disease. The PDB is a repository of experimentally determined structures, primarily from techniques like: X-ray Crystallography;Nuclear Magnetic Resonance (NMR) Spectroscopy; and Cryo-Electron Microscopy (Cryo-EM). Using Protein Data Bank, one can

1. Understand the Mechanism & Function: One can see the active site of an enzyme, the binding pocket for a drug, or the interface where two proteins interact.
2. Drug Discovery: One can look at the 3D structure of a disease-related protein (e.g., a viral protease, a cancer-causing kinase) and use computer software to design molecules that fit perfectly into its active site to block its function. Many modern drugs are developed with the help of PDB structures.
3. Interpreting Genetic Variants: When a genetic test finds a mutation (a change in the protein's sequence), researchers can map that change onto the 3D structure. They can see if the changes (mutated) amino acid is in a critical spot for folding or function, helping to determine if the variant is harmful (pathogenic) or benign.
4. Protein Evolution: By comparing structures of similar proteins from different species, scientists can understand how function has been conserved or altered through evolution. The PDB provides the crucial 3D structure of a protein, revealing its functional shape beyond just its sequence.

The structures of viral proteins in the PDB were critical for developing antiviral drugs. Today, the experimental structures in the PDB are powerfully complemented by AI-predicted models from systems like AlphaFold, creating an unprecedented structural map of human biology that accelerates the discovery of new diagnostics and therapies.