Ligands - Small Molecules: Nonpeptidic "Small Molecules" - Calcium, Catecholamines, Morphine, Adenosine Phosphates, Steroids, Estrogens, Progesterone, Thyroid Hormones, Enzyme Inhibitors, DNA-Binding Substances, Carcinogens, Cytostatic Agents, Ionophores; Peptidic and Proteohormones; Peptidic Toxins. Pictorial Representation of Proteins: Ligand - Transforming Growth Factor-beta; Ligand-Binding Protein - Human Chorionic Gonadotropin Receptor. Ligand-Binding Proteins - Large Molecules: Enzymes; Membrane Receptors; Signal Transduction Proteins; Multimodular Adhesion Proteins; DNA-Binding Proteins - DNA/RNA-Processing Enzymes, Antibodies against DNA, DNA-Bending Proteins (HMG-Box Proteins), Transcription Factors, Tumour Suppressor Proteins, Telomere-Binding Proteins, Homeobox Proteins; Immunological Proteins - Antibodies and B-Cell Receptors, MHC Proteins, T-Cell Receptor, Immunophilins; Miscellaneous Macromolecules - Apolipoproteins, Crystallins, Collagens, Haemoglobin, Spectrin, Stress Proteins, Chaperones and Heat Shock Proteins, Proteasomal Proteins, Viral Coat Proteins.