Receptor and ligand, hormone and hormone receptor, enzyme and substrate, neurotransmitter and synapse.
These pairs are alike in that they all function by the binding of two molecular mates.
These are examples of compounds acting as molecular locks and keys. This binding phenomena is based on a perfect spatial fitting between a drug, hormone, herb and a receptor.
These bindings have a high specificity with the slightest alteration in either the key or the lock destroying the relationship. The receptor-ligand or hormone-hormone receptor complex is the signal that tells the cell to turn on and off specific functions.
The difference between receptors is based on a small region known as the binding domain. This binding area determines which hormones can bind to it and which ones can’t.
Hormones can’t bind with damaged receptors and results in disease. Nutritional diabetes otherwise known as adult onset or Type II diabetes, is caused by insulin receptors losing their ability to bind to insulin, resulting in glucose being converted into fat.
Receptor binding domains are coded for by a section of DNA or gene. Different genes code for different receptors.
Receptor binding domains have been cloned, and the DNA sequences that code for them, known. Synthesizing and collecting them creates a combinatorial receptor library. Ligands are then ‘tested’ to see what receptors bind it binds to.
Artificial combinatorial receptors libraries are used to test a vast array of ligands. These libraries and their artificial receptors are used to discover new drugs and applications for old ones.
Artificial receptor libraries are powerful tools to identify ligands, and pathogenic organism. These libraries are used to counter bioterrorism and speed development of anti-cancer and anti-viral drugs.
Receptors are found embedded in cell and nuclear membranes, antibodies, in synapses and on molecules of cholesterol.
The number and diversity of receptors found in any given cell is a reflection of the type of activity carried out by the cell. The number of receptors is greatly exceeded by the number of potential ligands. These ligands include all of Nature’s libraries.
Many natural receptors that have been cloned do not bind with any of the usual ligands (hormones, drugs and neurotransmitters). These are called orphan receptors. Orphan receptors probably bind with a steroid-receptor complex.
Steroids exert their effect by passing through the outer membrane, binding with a carrier receptor and entering the nucleus.
In the nucleus, the steroid-complex can either interact directly with DNA to activate the involved genes or the steroid can rebind with a nuclear receptor, which interacts with DNA. If the binding with DNA increases transcription its called a promoter. If the absence of the hormone receptor complex represses translation, it’s called a repressor.
Transcription is the creation of a messenger RNA that serves as the blueprint for translating amino acids into the desired protein.
Promoters and repressors are based in the presence or absence of a ligand (the steroid) binding with a carrier and creating a new ligand (the complex). Promoters and repressors turn on and off the transcription of a gene. Mutators alter the genetic code by initiating a response to the assortment of chemicals, free radicals and uv light the cells’s nucleus is exposed to.