Proteins in the membrane of the Neuron and their functions
In order to have a full understanding of HOW neurons function, we have to take a look at the proteins that are in the membrane. These proteins play a significant part in determining the function of neurons. So, lets dive right in . . .
Membrane proteins and their functions
Passive or leakage ion channels: These are the routes for ions to move across the membrane. They are always open and are distributed throughout the whole neuron. The channel is made up of 5 alpha helices. There are nonpolar parts (exterior) and the and polar parts (interior), causing a polar route through the nonpolar lipid bilayer that is water-filled.
Sodium-potassium pump (Na-K pump): This pump pumps 3 Na+ ions out for every 2 K+ ions that it lets in.
V-gated ion channels: These channels can be open or closed. The factor that determines whether it is open or closed is the membrane voltage. If it is more positive internally, this can cause the channels to open. There are 2 classes that we will be talking about mainly: Na+ and K+ channels. These occur in the axon and define the axon. Because of these channels, the axon can create and transmit nerve impulses.
Ligand-gated channels: A ligand is a typically small molecule that is bound by a larger molecule – in this case, the channel protein. A ligand-gated channel is one that opens when it binds a specific ligand. Neurotransmitters are the class of ligands that we will be dealing with. These channels define, and are distributed in, the input region of the neuron (dendrites and soma). These various proteins are targeted as they are synthesized for the various regions of the neurons.
How these proteins are distributed
The Axon Terminals: These are the sites of neurotransmitter (NT) release. Proteins: V-gated channels (Ca2+), passive ion channels and Na-K pump.