FN3KRP phosphorylates PsiAm, RibAm

Proteins can undergo chemical modifications such as glycation, which occurs when glucose and other free aldoses spontaneously react with N-terminal and eta-amino groups of proteins to form Schiff bases, which slowly rearrange to ketosamines or, if the sugar was glucose, fructosamines. Fructosamines can further react slowly and become advanced glycation end products, which are thought to play a role in the pathophysiology of several disorders, especially diabetic complications. Ketosamine-3-kinase (FN3K) and ketosamine-3-kinase-related protein (FN3KRP) can phosphorylate protein-bound or free ketosamines on the third carbon of the sugar moiety and the resultant, unstable ketosamine 3-phosphates decompose under physiological conditions (a process called deglycation). Both enzymes can 3-phosphorylate psicosamines (PsiAm) and ribulosamines (RibAm) (Collard et al. 2003, 2004), but only FN3K can 3-phosphorylate fructosamines (FruAm) as well.

蛋白质可经历诸如糖基化等化学修饰过程，该过程发生于葡萄糖及其他游离醛糖与蛋白质的N端和ε-氨基自发反应生成席夫碱，席夫碱随后缓慢地重排为酮基胺或，若糖为葡萄糖，则为果糖胺。果糖胺可以进一步缓慢反应，转变为晚期糖基化终末产物，这些产物被认为在多种疾病的病理生理学中发挥作用，尤其是糖尿病并发症。酮基胺-3-激酶（FN3K）和酮基胺-3-激酶相关蛋白（FN3KRP）能够磷酸化糖基部分的第三碳上的蛋白质结合或游离酮基胺，生成的、不稳定的酮基胺3-磷酸盐在生理条件下分解（称为脱糖基化过程）。这两种酶均能3-磷酸化ψ-糖胺（PsiAm）和核糖胺（RibAm）（Collard等，2003，2004），但只有FN3K能够3-磷酸化果糖胺（FruAm）。