Histamine N-methyltransferase

Histamine N-methyltransferase (HMT, HNMT) is one of two enzymes involved in the metabolism of histamine. The other being diamine oxidase. Histamine N-methyltransferase catalyzes the methylation of histamine in the presence of S-adenosylmethionine (SAM) forming N-methylhistamine. HMT is present in most body tissues but is not present in fluid. Histamine N-methyltransferase is encoded by a single gene which has been mapped to chromosome 2.

References

Brown DD, Tomchick R, Axelrod J (November 1959). "The distribution and properties of a histamine-methylating enzyme". J. Biol. Chem. 234: 2948–50. PMID 13804910.

External links

MeSH Histamine+N-Methyltransferase
PDB [1] Horton, J.R., Sawada, K., Nishibori, M., Zhang, X., Cheng, X. (August 2002) "Crystal Structure Analysis of Human Histamine Methyltransferase (Thr105 Polymorphic Variant) Complexed with AdoHcy and Histamine"

Transferase: one carbon transferases (EC 2.1)

2.1.1: Methyl-

N-	Histamine N-methyltransferase - Phenylethanolamine N-methyltransferase - Amine N-methyltransferase - Phosphatidylethanolamine N-methyltransferase

O-	5-hydroxyindole-O-methyltransferase/Acetylserotonin O-methyltransferase - Catechol-O-methyl transferase

Homocysteine	Betaine-homocysteine methyltransferase - Homocysteine methyltransferase - Methionine synthase

Other	Phosphatidyl ethanolamine methyltransferase - DNMT3B - Histone methyltransferase - Thymidylate synthase - DNA methyltransferase - Thiopurine methyltransferase

2.1.2: Hydroxymethyl-,
Formyl- and Related

Hydroxymethyltransferase	Serine hydroxymethyltransferase - 3-methyl-2-oxobutanoate hydroxymethyltransferase

Formyltransferase	Phosphoribosylglycinamide formyltransferase - Inosine monophosphate synthase

Other	Glutamate formimidoyltransferase - Aminomethyltransferase

2.1.3: Carboxy- and Carbamoyl

Carboxy	methylmalonyl-CoA carboxytransferase

Carbamoyl	Aspartate carbamoyltransferase - Ornithine carbamoyltransferase - Oxamate carbamoyltransferase - Putrescine carbamoyltransferase - 3-hydroxymethylcephem carbamoyltransferase - Lysine carbamoyltransferase - N-acetylornithine carbamoyltransferase

2.1.4: Amidino

Arginine:glycine amidinotransferase

B enzm: 1.1/2/3/4/5/6/7/8/10/11/13/14/15-18, 2.1/2/3/4/5/6/7/8, 2.7.10, 2.7.11-12, 3.1/2/3/4/5/6/7, 3.1.3.48, 3.4.21/22/23/24, 4.1/2/3/4/5/6, 5.1/2/3/4/99, 6.1-3/4/5-6

Metabolism: amino acid metabolism · neurotransmitter enzymes

monoamine

histidine→histamine	anabolism: Histidine decarboxylase catabolism: Histamine N-methyltransferase · Amine oxidase

tyrosine→dopamine→epinephrine	anabolism: Tyrosine hydroxylase · Aromatic L-amino acid decarboxylase · Dopamine beta hydroxylase · Phenylethanolamine N-methyltransferase catabolism: Catechol-O-methyl transferase · Monoamine oxidase

glutamate→GABA	anabolism: Glutamate decarboxylase catabolism: 4-aminobutyrate aminotransferase · 4-aminobutyrate transaminase

tryptophan→serotonin→melatonin	Tryptophan hydroxylase · Aromatic L-amino acid decarboxylase · Acetylserotonin O-methyltransferase

arginine→NO

Nitric oxide synthase (NOS1, NOS2, NOS3)

choline→Acetylcholine

anabolism: Choline acetyltransferase
catabolism: Cholinesterase (Acetylcholinesterase, Butyrylcholinesterase)

M: MET

mt, k, c/g/r/p/y/i, f/h/s/l/o/e, a/u, n, m

k, cgrp/y/i, f/h/s/l/o/e, au, n, m, epon

m(A16/C10),i(k, c/g/r/p/y/i, f/h/s/o/e, a/u, n, m)

Histaminergics

Receptor
ligands

H₁	Agonists: 2-Pyridylethylamine • Betahistine • Histamine • HTMT • UR-AK49 Antagonists: "1st generation": 4-Methyldiphenhydramine • Alimemazine • Antazoline • Azatadine • Bamipine • Benzatropine (Benztropine) • Bepotastine • Bromazine • Brompheniramine • Buclizine • Captodiame • Carbinoxamine • Chlorcyclizine • Chloropyramine • Chlorothen • Chlorphenamine • Chlorphenoxamine • Cinnarizine • Clemastine • Clobenzepam • Clocinizine • Cyclizine • Cyproheptadine • Dacemazine • Deptropine • Dexbrompheniramine • Dexchlorpheniramine • Dimenhydrinate • Dimetindene • Diphenhydramine • Diphenylpyraline • Doxylamine • Embramine • Etybenzatropine (Ethylbenztropine) • Etymemazine • Histapyrrodine • Homochlorcyclizine • Hydroxyethylpromethazine • Hydroxyzine • Isopromethazine • Isothipendyl • Meclozine • Mepyramine (Pyrilamine) • Mequitazine • Methafurylene • Methapyrilene • Methdilazine • Moxastine • Niaprazine • Orphenadrine • Oxatomide • Oxomemazine • Phenindamine • Pheniramine • Phenyltoloxamine • Pimethixene • Piperoxan • Promethazine • Propiomazine • Pyrrobutamine • Talastine • Thenalidine • Thenyldiamine • Thiazinamium • Thonzylamine • Tolpropamine • Tripelennamine • Triprolidine; "2nd generation": Acrivastine • Astemizole • Azelastine • Cetirizine • Clemizole • Clobenztropine • Ebastine • Emedastine • Epinastine • Ketotifen • Latrepirdine • Levocabastine • Loratadine • Mebhydrolin • Mizolastine • Olopatadine • Rupatadine • Setastine • Terfenadine; "3rd generation": Desloratadine • Fexofenadine • Levocetirizine; Miscellaneous: Tricyclic antidepressants (Amitriptyline, Doxepin, Trimipramine, etc) • Tetracyclic antidepressants (Mianserin, Mirtazapine, etc) • Serotonin antagonist and reuptake inhibitors (Trazodone, Nefazodone) • Typical antipsychotics (Chlorpromazine, Thioridazine, etc) • Atypical antipsychotics (Clozapine, Olanzapine, Quetiapine, etc)

H₂	Agonists: Amthamine • Betazole • Dimaprit • Histamine • HTMT • Impromidine • UR-AK49 Antagonists: Burimamide • Cimetidine • Ebrotidine • Famotidine • Lafutidine • Lavoltidine/Loxtidine • Lupitidine • Metiamide • Niperotidine • Nizatidine • Oxmetidine • Ranitidine • Roxatidine

H₃	Agonists: α-Methylhistamine • Cipralisant • Histamine • Imetit • Immepip • Immethridine • Methimepip • Proxyfan Antagonists: A-349,821 • A-423,579 • ABT-239 • Betahistine • Burimamide • Ciproxifan • Clobenpropit • Conessine • GSK-189,254 • Impentamine • Iodophenpropit • JNJ-5,207,852 • MK-0249 • NNC-38-1,049 • PF-03654746 • Pitolisant • SCH-79,687 • Thioperamide • VUF-5,681

H₄	Agonists: 4-Methylhistamine • Histamine • VUF-8,430 Antagonists: JNJ-7,777,120 • Thioperamide • VUF-6,002

Reuptake
inhibitors

Vesicular

VMAT inhibitors	Ibogaine • Reserpine • Tetrabenazine

Enzyme
inhibitors

Anabolism

HDC inhibitors	Catechin • Meciadanol • Naringenin • Tritoqualine

Catabolism

HNMT inhibitors	Amodiaquine • Diphenhydramine • Harmaline • Metoprine • Quinacrine • SKF-91,488 • Tacrine

DAO inhibitors	Aminoguanidine

Others

Precursors	L-Histidine

Cofactors	Vitamin B6 (pyridoxine, pyridoxamine, pyridoxal → Pyridoxal phosphate)