Tartrate-resistant acid phosphatase (TRAP (also ACP5, TRAP5b))

Tartrate-resistant acid phosphatase (TRAP, ACP5) is a metalloenzyme predominately expressed in osteoclasts, activated macrophages, and dendritic cells, playing a pivotal role in bone resorption and the regulation of mineralized tissue turnover[1][3][4]. Distinguished from other acid phosphatases by its resistance to L(+)-tartrate inhibition and by its iron-dependent active site, TRAP hydrolyzes phosphate esters and anhydrides in acidic conditions[1][2][3]. TRAP is crucial for the normal remodeling of bone; genetic deficiency or inhibition leads to diseases such as osteopetrosis, while overactivity can contribute to excessive bone resorption and osteoporosis[1][4]. It is also involved in immune response, mediating macrophage and dendritic cell functions[3]. Serum levels of the TRAP5b isoform are widely used as a biomarker of osteoclastic activity and bone disease. While no approved drugs directly target TRAP, its enzymatic activity is a potential therapeutic target in metabolic bone diseases and certain immune or bone marrow disorders.

Other names

Acid phosphatase 5, tartrate resistantACP5TRAPasePurple acid phosphataseTRAP5bType 5 tartrate-resistant acid phosphatase

Enzymatic inhibition (phosphatase inhibitors) would act by blocking phosphate ester hydrolysis