【多巴胺受体D2】
多巴胺受体D2（Dopamine receptor D2，简称D2R），为转译自 DRD2 基因的一种多巴胺受体蛋白。D2R最早于1975年为Philip Seeman所发现，并将其命名为「抗精神疾患性多巴胺受体」（antipsychotic dopamine receptor）。D2R为所有抗精神病药物的作用标的。
== 功能 ==
D2R属于一种多巴胺受体，并会与Gi结合。Gi为G蛋白偶联受体的一种亚型，会抑制腺苷酸环化酶的活性。
在小鼠模式中，齿状回的neuronal calcium sensor-1（NCS-1）会影响D2R在细胞膜的表现量。这项机制会影响突触可塑性及记忆形成。
在苍蝇模式中，多巴胺性神经元上的D2R自体受器能避免神经元死亡，进而引发类帕金森氏症的症状。
== 同型体D2sh ==
Alternative splicing of this gene results in three transcript variants encoding different isoforms.
The long form (D2Lh) has the "canonical" sequence and functions as a classic post-synaptic receptor.The short form (D2Sh) is pre-synaptic and functions as an autoreceptor that regulates the levels of dopamine in the synaptic cleft.Agonism of D2sh receptors inhibits dopamine release; antagonism increases dopaminergic release.A third D2(Longer) form differs from the canonical sequence where 270V is replaced by VVQ.
== 基因组 ==
等位基因变异：
* A-241G
* C132T、G423A、T765C、C939T、C957T，以及G1101A
* Cys311Ser
* -141C insertion/deletionThe polymorphisms have been investigated with respect to association with schizophrenia.
Some researchers have previously associated the polymorphism Taq 1A (rs1800497) to the DRD2 gene.
However, the polymorphism resides in exon 8 of the ANKK1 gene.DRD2 TaqIA polymorphism has been reported to be associated with an increased risk for developing motor
fluctuations but not hallucinations in Parkinson's disease.
== 配体 ==
Most of the older antipsychotic drugs such as chlorpromazine and haloperidol are antagonists for the dopamine D2 receptor, but are, in general, very unselective, at best selective only for the "D2-like family" receptors and so binding to D2, D3 and D4, and often also to many other receptors such as those for serotonin and histamine, resulting in a range of side-effects and making them poor agents for scientific research. In similar manner, older dopamine agonists used for Parkinson's disease such as bromocriptine and cabergoline are poorly selective for one dopamine receptor over another, and, although most of these agents do act as D2 agonists, they affect other subtypes as well. Several selective D2 ligands are, however, now available, and this number is likely to increase as further research progresses.
===受体致活剂===
* 溴隐亭（Bromocriptine）：完全受体致活剂
* Cabergoline（Caberl）
* N,N-Propyldihydrexidine：D1/D5受体制活剂dihydrexidine的类似物，对节后神经元的D2R亲和性比节前神经元的D2自体受器高。
* Piribedil：同时也是 D3 受体致活剂及肾上腺素α2受体拮抗剂
* Pramipexole：同时也是D3、D4受体致活剂
* Quinelorane：affinity for D2 > D3
* Quinpirole：同时也是D3受体致活剂
* Ropinirole：完全受体致活剂
* Sumanirole：高选择性完全受体致活剂
* Talipexole：对D2的亲和性高于其他的多巴胺受体，但同时也是肾上腺素α2受体制活剂及5-HT3受体拮抗剂。
===部分受体致活剂===
* Aplindore
* 阿立哌唑（Aripiprazole，在美国合法）
* Brexpiprazole/OPC-34712
* Cariprazine
* RP5063
* GSK-789,472 – Also D3 antagonist, with good selectivity over other receptors
* 氯胺酮（Ketamine，同时也为NMDA受体拮抗剂）
* LSD – in vitro, LSD was found to be a partial agonist and potentiates dopamine-mediated prolactin secretion in lactotrophs.LSD is also a 5-HT2A agonist.
* 莫达非尼（Modafinil）
* Roxindole (only at the D2 autoreceptors)
* OSU-6162：亦为5-HT2A部分受体致活剂，acts as "dopamine stabilizer"
* Salvinorin A：亦为κ-鸦片类受体致活剂。
===受体拮抗剂===
* Atypical antipsychotics
* Desmethoxyfallypride
* Domperidone – D2 and D3 antagonist; does not cross the blood-brain barrier
* Eticlopride
* Fallypride
* Hydroxyzine (Vistaril, Atarax)
* Itopride
* L-741,626  – highly selective D2 antagonist
* C11 Raclopride radiolabled – commonly employed in positron emission tomography studies
* Typical antipsychotics
* SV 293
*Yohimbine
D2sh selective (presynaptic autoreceptors)
* Amisulpride (low doses)
* UH-232
===异位调控因子===
* Homocysteine – 负向异位调控因子
* PAOPA
* SB-269,652
=== Functionally selective ligands ===
* 参见参考文献。
==Protein–protein interactions==
The dopamine receptor D2 has been shown to interact with EPB41L1,PPP1R9Band NCS-1.
===Receptor oligomers===
The D2 receptor forms receptor heterodimers in vivo (in living animals) with other G protein-coupled receptors; these include:
*D1–D2 dopamine receptor heteromer
*D2–adenosine A2A
*D2–ghrelin receptor
*D2sh–TAAR1
The D2 receptor has been shown to form hetorodimers in vitro (and possibly in vivo) with DRD3,DRD5,and 5-HT2A.