Cells of neurotransmitters (dopamine,serotonin,nmda,etc)

[lemonman]

Hello,

In the picture below you can see loads of other enzymes,cells,etc.
I would just like to ask please how the enzymes,cells,etc in the picture below transmit the information (regarding the arrows).

For example: How does beta2-arrestin send its information to Akt1 (inactive) (in the arrow, this goes for all of them), is it through cells or what?

Picture:
https://i.imgur.com/pawgvWY.png


Thanks.

 

[Hodor]

Many neurotransmitter receptors belong to a class called "G-Protein-coupled receptors".

When a neurotransmitter activates the receptor (which is integrated into the cell's membrane), it will cause a so-called "G-protein" to be released inside the cell. Often, this protein will then activate an enzyme called "adenylate cyclase", which produces a "second messenger" called cAMP, which will in turn kick off a cascade of regulatory signals.

These signal pathways are extremely complex and our understanding of them is far from complete; part of the reason they are so complex is because they include feedback mechanisms to regulate themselves.

One such feedback mechanism involves the beta-arrestins. Basically, these are proteins that bind to the receptor and prevent it from being activated again, as well as encouraging the cell to reabsorb and recycle the receptor.

 

[Seppi]

The "Dopaminergic Synapse" schematic from the Kyoto Encyclopedia of Genes and Genomes - this is a simplified schematic of a dopamine synapse which ignores cell type-specific selective expression of specific dopamine receptors (e.g., neurons that only express D1-like or D2-like receptors) and does not illustrate non-dopaminergic receptors in the schematic due to the fact that these vary greatly between different dopaminergic pathways and even within specific dopaminergic pathways (e.g., the mesolimbic pathway projects onto at least 5 distinct phenotypes of medium spiny neurons in the nucleus accumbens - D1-type in the NAcc shell, D1-type in the Nacc core, D2-type in the Nacc shell, D2-type in the Nacc core, and mixed-type in the Nacc shell; mixed-type neurons are not present in the core).

In any event, to see the image legend for the diagram in my link, which indicates the specific types of interactions that are depicted by the connections in the diagram, click the "Help" button in the top right corner of the page. For context on what is being depicted (i.e., to read the caption), click the "Show description" button in the header along the top of the diagram.

If you want to see schematic diagrams of other neurotransmitter synapses, the full set of diagrams include: the serotonergic synapse, cholinergic synapse, GABAergic synapse, and glutamatergic synapse. Again, all of these are simple schematic diagrams that illustrate signaling pathways of neurotransmitter receptors and co-localized proteins in neurons for the associated neurotransmitter in a general context; they do not accurately reflect any particular set of neurons for these neurotransmitters since co-localized GPCRs and ion-channels for other neurotransmitters that signal through through the serotonergic/cholinergic/GABAergic/glutamatergic neurons in various brain regions/pathways are not depicted.

 

[Seppi]

Also, the dopaminergic synapse isn't entirely accurate since it's completely missing TAAR1 proteins and the corresponding TAAR1 signaling pathways in the presynaptic neuron. TAAR1, DRD1, DRD2, DRD3, DRD4, and DRD5 are the primary biomolecular targets of dopamine in the human brain (see https://en.wikipedia.org/wiki/Dopamine#Functions).