Salvage - Sepiapterin is reduced to q-BH2

In the first of two salvage steps to maintain BH4 levels in the cell, sepiapterin is taken up by the cell and reduced by sepiapterin reductase (SRP) to form BH2 (Sawabe et al. 2008).在维持细胞内BH4水平的第一道修复步骤中，次黄苷酸被细胞摄取，并由次黄苷酸还原酶（SRP）还原，从而形成BH2（Sawabe等人，2008年）。