H-89

H-89 is a synthetic small molecule that acts as a potent and selective inhibitor of cAMP-dependent protein kinase (protein kinase A or PKA). It competitively inhibits the ATP-binding site on the catalytic subunit of PKA with high affinity (Ki ≈ 48 nM), making it widely used in research to dissect cAMP/PKA signaling pathways. While initially considered highly selective for PKA, subsequent studies have shown that at higher concentrations it can also inhibit other kinases such as S6K1, MSK1, ROCKII (Rho-associated coiled-coil containing protein kinase II), CaM kinase II (calmodulin-dependent protein kinase II), casein kinase I, myosin light chain kinase (MYLK), PKCµ and Akt1. Additionally, it has been reported to directly inhibit certain potassium currents. H-89 is not approved for clinical use and is primarily utilized as a laboratory tool compound in cell signaling research[1][5][8]. Experimental studies have explored its effects in vivo on seizure thresholds and morphine withdrawal symptoms in animal models[1].

Other names

N-[2-(4-bromocinnamylamino)ethyl]isoquinoline-5-sulfonamideN-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamideProtein kinase inhibitor H-89 dihydrochloridePKA Inhibitor III