| 背景信息 |
Phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthase (PAICS) is a bifunctional cytosolic enzyme essential for the de novo purine biosynthetic pathway. It catalyzes the sequential conversion of aminoimidazole ribotide (AIR) to carboxyaminoimidazole ribotide (CAIR) and subsequently to succinylaminoimidazolecarboxamide ribotide (SAICAR). Structurally, PAICS forms a homo-octamer that enables efficient substrate channeling between its carboxylase and synthetase domains. The enzyme is a key component of the purinosome, a multienzyme complex that assembles to meet high cellular demands for purines. Clinically, PAICS is overexpressed in numerous malignancies, including lung adenocarcinoma and prostate cancer, where it promotes metabolic reprogramming, cell proliferation, and epithelial-mesenchymal transition. |