Cleavage of connectin by calpain and cathepsin D.
mu-Calpain quickly split the alpha-connectin in myofibrils into beta-connectin, and then produced a 1700-kDa component. Cathepsin D also split alpha-connectin into beta-connectin, further degrading it to fragments smaller than the 1700-kDa component with increasing incubation time. The action of cathepsin D on the connectin molecule was distinctly different from that of mu-calpain in terms of the splitting rate and manner. When freshly excised muscle was exposed to a temperature of 37 degrees C, complete disappearance of connectin (alpha, beta and 1700-kDa component) was observed within 36 h. In contrast, at 2 degrees C, about 75% of connectin was retained as beta-form even after 3 weeks. The present data suggest that the degradation of connectin in muscle might be caused by mu-calpain in the early stage of aging, and then with time, this action is replaced by m-calpain or cathepsin D. However, the possibility of other intrinsic proteases participating in the degradation of connectin still remains.
Kim
K
K
Department of Biosystem Science, Graduate School of Science and Technology, University of Niigata, Japan.
Homma
Y
Y
Ikeuchi
Y
Y
Suzuki
A
A
D000818:Animals; D002154:Calpain / Q000494:pharmacology*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002402:Cathepsin D / Q000494:pharmacology*; D002645:Chickens; D064211:Connectin; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D009124:Muscle Proteins / Q000737:chemistry* / Q000378:metabolism*; D011494:Protein Kinases; D011817:Rabbits; D013696:Temperature
D002352:Carrier Proteins; D064211:Connectin; D008565:Membrane Proteins; D009124:Muscle Proteins; D011494:Protein Kinases; D002154:Calpain; D002402:Cathepsin D