Acyl-CoA-binding protein is a potent m-calpain activator.
Acyl-CoA-binding protein, a 20-kDa homodimer that exerts many physiological functions, promotes activation of the classic calpain forms, most markedly that of the m-isozyme. This protein factor was purified from rat skeletal muscle and was also expressed in Escherichia coli. Both native and recombinant acyl-CoA-binding proteins show the same molecular properties and an identical capacity to decrease the [Ca(2+)] required for m-calpain activity. The binding of long-chain acyl-CoAs to acyl-CoA-binding protein does not modify the activating effect on calpains. Acyl-CoA-binding protein seems to be involved in the m-calpain regulation process, whereas the previously identified UK114 activator is a specific modulator of micro-calpain. Acyl-CoA-binding protein is proposed as a new component of the Ca(2+)-dependent proteolytic system. A comparative analysis among levels of classic calpains and their activator proteins is also reported.
Melloni
E
E
Department of Experimental Medicine, Biochemistry Section, University of Genoa, Viale Benedetto XV,1, 16132 Genoa, Italy. melloni@csita.unige.it
Averna
M
M
Salamino
F
F
Sparatore
B
B
Minafra
R
R
Pontremoli
S
S
D000595:Amino Acid Sequence; D000818:Animals; D002154:Calpain / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D026261:Diazepam Binding Inhibitor; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology*; D009363:Neoplasm Proteins / Q000032:analysis; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014018:Tissue Distribution
D002352:Carrier Proteins; D026261:Diazepam Binding Inhibitor; D020536:Enzyme Activators; D007527:Isoenzymes; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; C101630:UK114 antigen; D002154:Calpain