Riboflavin kinase (RFK) (RFK)

Riboflavin kinase (RFK) is a critical metabolic enzyme that catalyzes the phosphorylation of riboflavin (vitamin B2) to form flavin mononucleotide (FMN), the first step in the biosynthesis of essential flavin cofactors. These cofactors, FMN and flavin adenine dinucleotide (FAD), are indispensable for numerous cellular processes, including mitochondrial electron transport, fatty acid beta-oxidation, and the maintenance of redox homeostasis. Beyond its primary metabolic function, RFK plays a significant role in signal transduction by interacting with the death domain of tumor necrosis factor receptor 1 (TNFR1), thereby facilitating the assembly of the NADPH oxidase complex and the production of reactive oxygen species. In the context of disease, RFK is a target of interest for antimalarial therapy, as certain riboflavin analogs like roseoflavin can selectively inhibit the parasite enzyme or be converted into toxic cofactor analogs. It is also investigated in oncology, where its inhibition may starve tumors of the energy required for rapid proliferation. However, therapeutic targeting of RFK is challenging due to its essentiality; genetic deletion in animal models is embryonic lethal, and pharmacological inhibition carries the risk of inducing systemic riboflavin deficiency (ariboflavinosis) and mitochondrial dysfunction.

Other names

FlavokinaseATP:riboflavin 5'-phosphotransferase

Competitive inhibition of the riboflavin binding site and metabolic conversion of substrate analogs into toxic cofactor derivatives.