Activation of tyrosine hydroxylase by Ca2+-dependent neutral protease, calpain.
Two molecular species of Ca2+-dependent neutral protease (calpains I and II) and its endogenous inhibitor (calpastatin) in cytosol fraction of bovine adrenal medulla were separated by hydrophobic interaction chromatography. Both calpains I and II, having low and high Ca2+ requirements for casein hydrolysis, respectively, were found to activate tyrosine hydroxylase(TH) that had been purified from cytosol fraction of bovine adrenal medulla. This activation of TH by calpain was inhibited by leupeptin and the endogenous inhibitor, calpastatin. The activated TH with calpain II, characterized by high-performance gel permeation chromatography, had a reduced Mr of 120,000 from the Mr of 230,000 of native enzyme.
Togari
A
A
Ichikawa
S
S
Nagatsu
T
T
D000313:Adrenal Medulla / Q000201:enzymology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004789:Enzyme Activation; D008970:Molecular Weight; D014446:Tyrosine 3-Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*
D014446:Tyrosine 3-Monooxygenase; D002154:Calpain; D002118:Calcium