synapten

Synapten is a term that does not have a widely accepted definition in modern biology or neuroscience. In peer-reviewed literature it is not the standard name for any molecule, protein, or process involved in synaptic transmission. When it appears, it is typically as an informal or historical label applied by some authors to a hypothetical signaling entity proposed to mediate communication across the synaptic junction; however, there is no consensus on its identity, function, or even its existence as a real biological substance.

Because of the lack of a standard definition, synapten is not part of current synaptic nomenclature. It is occasionally encountered in older or speculative discussions about neuronal signaling, and in some popular science or science-fiction contexts as a placeholder for a postulated messenger substance. By contrast, modern neuroscience describes synaptic transmission in terms of established components such as neurotransmitters, receptors, synaptic vesicles, the SNARE apparatus, the synaptic cleft, and the postsynaptic density.

If the term is encountered in a text, readers should examine the source to understand how the author defines it, since meanings may vary and are not standardized. Absent a clear definition, assigning specific chemical properties or roles to synapten would be speculative. See also synapse, neurotransmitter, synaptic vesicle, synaptic cleft, SNARE proteins, and postsynaptic density.