Phosphocreatine (PCr (also commonly CP for creatine phosphate))

Phosphocreatine, also known as creatine phosphate (PCr or CP), is a phosphorylated derivative of creatine that acts as a rapidly mobilizable reserve of high-energy phosphates in skeletal muscle, cardiac muscle, and brain. Its primary biological function is to serve as an energy reservoir for the rapid regeneration of adenosine triphosphate (ATP), the key energy currency of the cell. In the presence of the enzyme creatine kinase, phosphocreatine can donate its phosphate group to adenosine diphosphate (ADP), thereby regenerating ATP during periods of high energy consumption, such as muscle contraction or neuronal activity. This process is reversible, allowing the storage of excess ATP—via phosphocreatine synthesis—during periods of rest or low activity[4][1][7]. While phosphocreatine is essential in energy metabolism and is used therapeutically in some countries for conditions with high energy requirements, such as cardiovascular disease, it is not considered a classic therapeutic target such as a receptor, enzyme, or transporter. Instead, it is an endogenous energy carrier molecule and more appropriately classified as a metabolite or co-substrate. Phosphocreatine supplementation is sometimes used by athletes to potentially enhance short-term muscle performance, but robust clinical evidence is lacking[1][2][4][7]. Creatine kinase is the key enzyme regulating the formation and utilization of phosphocreatine, and deficiencies involving this system—such as mutations in the creatine transporter or synthesis pathway—can lead to severe neurological and muscular diseases. Creatinine, the metabolic byproduct of phosphocreatine breakdown, serves as a routine clinical biomarker for renal function[4][7][3]. Because phosphocreatine is a molecule and not a protein therapeutic target, it falls outside the typical drug-target paradigm (i.e., it is not a receptor, enzyme, transporter, or transcription factor). Any drug–target interactions relate instead to enzymes like creatine kinase rather than directly to phosphocreatine itself[7][9][4].

Other names

Creatine phosphateCPPCrPcrN-phosphocreatinePhosphagenFosfocreatineCreatine-PN-(Phosphonoamidino)sarcosinePhosphorylcreatineN-PhosphorylcreatineCreatinephosphoric acidCreatine phosphic acid

Serves as a phosphate donor for rapid regeneration of ATP during high energy demand in tissue, especially muscle and brain[4][7][1]