Tryptamiinit kuten serotoniini ja melatoniini

Tryptofaani-aminohapon biogeeninen amini on tryptamiini, jalomuodot ovat serotoniini ja melatoniini, moilla on omat biologiset reséptorinsa kehojärjestelmässä serotonergisessä neuronijsystemissä.
Serotoniinireseptorit eli 5-HT-reseptorit luokitellaan näin Wikipediassa:

Classification With the exception of the 5-HT₃ receptor, a ligand-gated ion channel, all other serotonin receptors are G protein-coupled receptors that activate an intracellular second messenger cascade to produce an excitatory or inhibitory response.

Families

Family	Type	Mechanism	Potential
5-HT1	Gi/Go-protein coupled.	Decreasing cellular levels of cAMP.	Inhibitory
5-HT2	Gq/G11-protein coupled.	Increasing cellular levels of IP3 and DAG.	Excitatory
5-HT3	Ligand-gated Na+ and K+ cation channel.	Depolarizing plasma membrane.	Excitatory
5-HT4	Gs-protein coupled.	Increasing cellular levels of cAMP.	Excitatory
5-HT5	Gi/Go-protein coupled.[4]	Decreasing cellular levels of cAMP.	Inhibitory
5-HT6	Gs-protein coupled.	Increasing cellular levels of cAMP.	Excitatory
5-HT7	Gs-protein coupled.	Increasing cellular levels of cAMP.	Excitatory

MELATONIINIRESEPTORI MT-1
http://www.ncbi.nlm.nih.gov/pubmed/20549340