| |
H1
|
H2
|
H3
|
|
Coding sequence
|
491 a.a. (bovine)
488 a.a. (guinea pig)
486 a.a. (rat)
|
358 a.a. (rat)
359 a.a. (dog, human, guinea pig)
|
?
|
|
Chromosome localization
|
Chromosome 3
|
Chromosome 5
|
?
|
|
Highest brain densities
|
Thalamus
Cerebellum
Hippocampus
|
Striatum
Cerebral cortex
Amygdala
|
Striatum
Frontal cortex
Substantia nigra
|
|
Autoreceptor
|
No
|
No
|
Yes
|
|
Affinity for histamine
|
Micromolar
|
Micromolar
|
Nanomolar
|
|
Characteristic agonists
|
2(3-trifluoronethyl)histamine
|
Impromidine
Sopromidine
|
(R)a-methylhistamine
Imetit
|
|
Characteristic antagonists
|
Mepyramine (pyrilamine)
|
Cimetidine
|
Thioperamide
|
|
Radioligands
|
[3H]Mepyramine
[125I]Iodobolpyramine
|
[3H]Tiotidine
[125I]Iodoaminopotentidine
|
[3H](R)a-methylhistamine
[125I]Iodoproxyfan
|
|
Second messengers
|
Inositol phosphates (+)
Arachidonic acid (+)
cAMP (potentiation)
|
cAMP (+)
Arachidonic acid (-)
Ca2+ (+)
|
Inositol phosphates (-)
|