Malantide TFA, a synthetic dodecapeptide, originates from the phosphorylation site targeted by cAMP-dependent protein kinase (PKA) on the β-subunit of phosphorylase kinase. Exhibiting a high specificity for PKA with a Michaelis constant (Km) of 15 μM, this compound demonstrates more than 90% inhibition of substrate phosphorylation in the presence of protein inhibitor (PKI) across various rat tissue extracts [1]. Moreover, Malantide TFA acts as an effective substrate for Protein Kinase C (PKC) with a Km of 16 μM [2].