次黃嘌呤-鳥嘌呤磷酸核苷轉移酶

次黃嘌呤-鳥嘌呤磷酸核苷轉移酶（Hypoxanthine-guanine phosphoribosyltransferase，簡稱HGPRT），化学式为：C1096H1732O322N290S10Mg2，為人體內一個轉譯自HPRT1基因的酵素

HGPRT為一種轉移酶，可以催化將次黃嘌呤轉換為肌苷酸（IMP），也可將鳥嘌呤的反應轉為單磷酸鳥苷。這兩個反應都是將PRPP的5-磷酸核苷轉移至嘌呤上。HGPRT在核苷酸再利用合成途徑中扮演重要角色。

 功能 

HGPRT催化下列反應：

反應物產物 備註 次黃嘌呤  肌苷酸  — 鳥嘌呤   單磷酸鳥苷  常稱HGPRT，僅有部分物種有此功能。 黄嘌呤    特定HPRT

HGPRTase functions primarily to salvage purines from degraded DNA to reintroduce into purine synthetic pathways. In this role, it catalyzes the reaction between guanine and phosphoribosyl pyrophosphate (PRPP) to form GMP, or between hypoxanthine and phosphoribosyl pyrophosphate (PRPP) to form inosine monophosphate.

 Substrates and inhibitors 

Comparative homology modelling of this enzyme in  suggest that among all of the computationally screened compounds, , 1,3-dinitroadamantane, acyclovir and analogs of acyclovir had higher binding affinities than the real substrate (guanosine monophosphate).

 疾病中的角色 
此基因的突變往往導致高尿酸血症：

 一些男性帶有部分程度的HGPRT缺陷（約低於正常活動量20%）並因此導致血液中高濃度的尿酸。隨之而來的是痛風以及腎結石。這症狀稱為凱利-塞米勒症候群。
 萊希-尼亨症候群起源由HPRT1突變導致的HGPRT缺陷。
 某些基因突變可能導致痛風。發病的風險與hypoxanthine-guanine phosphoribosyltransferase的缺陷程度成正比。

thumbtime=3 |thumb |300px |alt=PRTFDC1-Is-a-Genetic-Modifier-of-HPRT-Deficiency-in-the-Mouse-pone.0022381.s008.ogv|透過基因工程讓一隻老鼠帶有缺陷的HPRT基因後，老鼠的表現。
 HPRT expression on the mRNA and protein level is induced by hypoxia inducible factor 1 ().  HIF-1 is a transcription factor that directs an array of cellular responses that are used for adaptation during oxygen deprivation.  This finding implies that HPRT is a critical pathway that helps preserve the cell's purine nucleotide resources under hypoxic conditions as found in pathology such as myocardial ischemia.

The in silico and in-vitro correlation of these compounds were test in Leishmania HGPRT and validates the result.

 Hybridomas 

s are immortal (immune to ), HGPRT+ cells that result from fusion of mortal, HGPRT+ plasma cells and immortal, HGPRT− myeloma cells. They are created to produce monoclonal antibodies in biotechnology.  inhibits de novo synthesis of nucleic acids, killing myeloma cells that cannot switch over to the salvage pathway, due to lack of HRPT1. The plasma cells in the culture eventually die from senesence, leaving pure hybridoma cells.

 參見 

 參考文獻 

 延伸閱讀 





















 外部連結 

 Purine metabolism at genome.jp 
  GeneReviews/NCBI/NIH/UW entry on Lesch-Nyhan Syndrome