Calcium-induced splitting of connectin filaments into beta-connectin and a 1,200-kDa subfragment.
When rabbit skeletal muscle myofibrils were treated with a solution containing 0.1 mM Ca2+ and 30 micrograms of leupeptin/ml, alpha-connectin, which forms very thin filaments in myofibrils, was split into beta-connectin and a 1,200-kDa subfragment. A part of beta-connectin located near the junction between beta-connectin and the subfragment seems to have an affinity for calcium ions and to be susceptible to the binding of large amounts of calcium ions. The calcium-binding site on beta-connectin is localized near the N2 line in the I band, and the subfragment is localized adjacent to the Z disk. It is possible that connectin filaments change their elasticity during the contraction-relaxation cycle of skeletal muscle at the physiological concentration of calcium ions. Because postmortem skeletal muscles lose their elasticity and become plastic in association with the calcium-specific splitting of connectin filaments, the splitting is considered to be a factor in meat tenderization during postrigor ageing.
Takahashi
K
K
Department of Animal Science, Faculty of Agriculture, Hokkaido University.
Hattori
A
A
Tatsumi
R
R
Takai
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D064211:Connectin; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008970:Molecular Weight; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011494:Protein Kinases; D011817:Rabbits; D013696:Temperature
D064211:Connectin; D009124:Muscle Proteins; D010446:Peptide Fragments; D011494:Protein Kinases; D002118:Calcium