VMATs

VMAT stands for Vesicular Monoamine Transporter. These are protein complexes embedded in the membranes of intracellular vesicles, primarily in neurons. VMATs are responsible for packaging monoamine neurotransmitters, such as dopamine, serotonin, norepinephrine, and histamine, from the cytoplasm into these vesicles. This process is crucial for storing neurotransmitters and protecting them from enzymatic degradation within the cell.

There are two main isoforms: VMAT1 and VMAT2. VMAT1 is primarily found in the peripheral nervous system and adrenal medulla, while VMAT2 is more widely distributed and is the predominant form in the central nervous system. Both isoforms function as antiporters, using a proton gradient across the vesicle membrane to drive the uptake of monoamines. This proton gradient is maintained by a vesicular ATPase.

The activity of VMATs is essential for regulated neurotransmitter release. Once packaged into vesicles, monoamines are protected and ready for exocytosis, the process by which the vesicles fuse with the cell membrane and release their contents into the synaptic cleft. Drugs that target VMATs, such as reserpine, can deplete monoamine stores by blocking their uptake into vesicles, leading to reduced neurotransmission. Conversely, some stimulants can indirectly affect VMAT function. VMATs are therefore important targets for understanding and treating various neurological and psychiatric conditions.