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Available structures
PDBOrtholog search: PDBe RCSB
AliasesTPH2, ADHD7, NTPH, tryptophan hydroxylase 2
External IDsOMIM: 607478 MGI: 2651811 HomoloGene: 27831 GeneCards: TPH2
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 12: 71.94 – 72.19 MbChr 10: 115.08 – 115.19 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

Tryptophan hydroxylase 2 (TPH2) is an isozyme of tryptophan hydroxylase found in vertebrates. In humans, TPH2 is primarily expressed in the serotonergic neurons of the brain, with the highest expression in the raphe nucleus of the midbrain. Until the discovery of TPH2 in 2003,[5] serotonin levels in the central nervous system were believed to be regulated by serotonin synthesis in peripheral tissues, in which tryptophan hydroxylase is the dominant form.[6]


Tryptophan hydroxylase (TPH; EC is the rate-limiting enzyme in the synthesis of serotonin (5-hydroxytryptamine, or 5HT). 5HT is causally involved in numerous central nervous activities, and it has several functions in peripheral tissues, including the maintenance of vascular tone and gut motility.[supplied by OMIM][7]

See also[edit]


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000139287 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000006764 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Walther DJ, Peter JU, Bashammakh S, Hörtnagl H, Voits M, Fink H, Bader M (Jan 2003). "Synthesis of serotonin by a second tryptophan hydroxylase isoform". Science. 299 (5603): 76. doi:10.1126/science.1078197. PMID 12511643. S2CID 7095712.
  6. ^ Zill P, Büttner A, Eisenmenger W, Möller HJ, Ackenheil M, Bondy B (2005). "Analysis of tryptophan hydroxylase I and II mRNA expression in the human brain: a post-mortem study". Journal of Psychiatric Research. 41 (1–2): 168–73. doi:10.1016/j.jpsychires.2005.05.004. PMID 16023677.
  7. ^ "Entrez Gene: TPH2 tryptophan hydroxylase 2". CS1 maint: discouraged parameter (link)

Further reading[edit]