Biosynthesis and Storage
Start with the big picture
The pathways differ in their precursors and enzymes: acetylcholine is formed from choline and acetyl-CoA, while catecholamines proceed from tyrosine through dopamine and norepinephrine to epinephrine. Serotonin, histamine, GABA, glutamate, and glycine each have distinct synthesis routes and storage or uptake mechanisms. Several pathways rely on cofactors such as BH4 or PLP, and some have specified rate-limiting steps. Vesicular transporters—including VAChT, VMAT2, VGLUT, and VGAT—support storage of different transmitter groups. In contrast, nitric oxide is synthesized on demand rather than stored in vesicles. Neuropeptides are processed through the RER and Golgi and packaged into large dense-core vesicles, with release associated with high-frequency calcium influx.
What you'll learn
- Trace the synthesis pathways for acetylcholine, catecholamines, serotonin, and histamine.
- Identify key enzymes, cofactors, and rate-limiting steps in transmitter biosynthesis.
- Match major neurotransmitters with their vesicular transporters or uptake mechanisms.
- Distinguish vesicular storage of neurotransmitters from on-demand nitric oxide synthesis.
- Describe how neuropeptides are processed and packaged for release.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
