The Three-Dimensional Structure of a Protein A depiction of the subsets of a protein structure. Related Links Online Textbook: Proteins and Proteomics: Introduction to Protein Structure Related Terms: Active site Domain Motifs Nuclear magnetic resonance (NMR) X-ray crystallography Peptide mass mapping Primary structure Quaternary structure Secondary structure Tertiary structure Related Images: John Kendrew Ras protein Max Perutz Protein structure Related Animations: None