We have purified adenosine triphosphate: arginine phosphotransferase (EC2-7-3-3, arginine kinase) and molecularly cloned the cDNA from the tail muscle of crayfish,
Procambarus clarkii. An open reading frame encodes 357 amino acid residues with a calculated molecular mass of 40, 118 dalton. The predicted amino acid sequence shows 60% similarity with that of human creatine kinase B-subunit. The expression of a full-length cDNA in COS7 cells gave rise to a product of 40kDa and conferred the arginine kinase activity on mammalian cells. The amino acid sequence surrounding cys
271 is well conserved as an active site for the catalytic function among a family of phosphagen kinase. We have found that chemical modification of a single cysteinyl residue of arginine kinase inhibits the enzymatic function and ATP protects the enzyme against this modification.
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