MadSci Network: Neuroscience |
I assume you are familiar with basic genetics, i.e. DNA is transcribed into RNA which is then translated into an amino acid chain (protein) on the ribosomes. The information on the strands of DNA is not in one piece though. It is usually fragmented into what are termed exons and introns where the exons code for the protein sequence and some other accessory information, e.g. information required for initiating translation. Exons can in some cases be arranged in different combinations when they are assembled into the messenger RNA, a process called (differential) splicing. And this is exactly the point where (structural as well as functional) variation among receptors of the same family can occur and/or is created (besides different DNA sequences due to mutation, duplication, or other genetic effects of course). Usually different splice variants can be shown to exist in different tissues or at different developmental stages in an organism. Which variant usually is expressed, i.e. which shows up on the cell's surface, is determined a) by all kinds of signals that impinge on the cell (at the surface or even from within) and which lead to activation and/or repression (through DNA binding proteins) of so called control elements in a gene's control region. b) how the splice apparatus works. In this way DNA can affect the expression of neurotransmitter receptors. But note that DNA expression itself is regulated through various pathways that are turned on or off by external or internal stimuli. In many cases the exons are structured in such a way that one exon may code for what is known as a structural/functional domain, e.g. a substrate or ligand binding region in the protein. These may then be rearranged to yield different receptor variants (as described above) I hope this answers your question. Feel free to email me if you have further questions.
Try the links in the MadSci Library for more information on Neuroscience.