Question

consider the structure of the neurotransmitters: Acetylcholine, Noradrenaline, Adrenalin, dopamine, glycine, serotonin, y-aminobutyric acid and glutamic acid and suggest what type of binding interactions could be involved in binding them to a receptor binding site, and identify possible amino acids in the binding site which could take place in these binding interactions

Answer 1

1. Acetylcholine receptors: Acetylcholine interacts with its receptors through ligand gated channels. Binding of acetylcholine to the N termini of each of the two alpha subunits of the receptor. In the intermediate region of the receptor, within the pore lumen, valine and leucine residues (Val 255 and Leu 251) define a hydrophobic region through which the dehydrated ion must pass. It is a non-covalent interaction.
2. Andregenic receptors: There are two main groups of adrenergic receptors, ? and ?. ?₁-adrenergic receptors are members of the G_q protein-coupled receptor superfamily. Upon activation, a heterotrimeric G protein, G_q, activates phospholipase C (PLC). The PLC cleaves phosphatidylinositol 4,5-bisphosphate (PIP2), which in turn causes an increase in inositol triphosphate (IP3) and diacylglycerol (DAG). The former interacts with calcium channels of endoplasmic and sarcoplasmic reticulum, thus changing the calcium content in a cell. This triggers all other effects, including a prominent slow after depolarizing current (sADP) in neurons. It is also a non-covalent interaction.
3. Dopamine receptors: Dopamine receptor D1 and Dopamine receptor D5 are Gs coupled receptors that stimulate adenylyl cyclase to produce cAMP, increasing intracellular calcium among other cAMP mediated processes. It is a polar-polar interaction.
4. Sertonin receptors: 5-hydroxytryptamine receptors or 5-HT receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels.
5. Y-amino butyric acid receptors:  Fast-responding GABA receptors are members of a family of Cys-loop ligand-gated ion channels. GABA_A receptors possess a characteristic loop formed by a disulfide bond between two cysteine residues.
6. Glutamic acid receptors: are of two types: Ionotropic glutamate receptors, by definition, are ligand-gated nonselective cation channels that allow the flow of K⁺, Na⁺ and sometimes Ca²⁺ in response to glutamate binding. Metabotropic glutamate receptors, which belong to subfamily C of G protein-coupled receptors are divided into three groups, with a total of eight subtypes. The mGluRs are composed of three distinct regions: the extracellular region, the transmembrane region, and the intracellular region.