Changes in contractile properties with selective digestion of connectin (titin) in skinned fibers of frog skeletal muscle.
Changes in contractile properties of mechanically skinned fibers were examined when connectin in the fibers was selectively digested by a low concentration (0.25 microgram/ml) of trypsin. Resting tension and isometric active tension were reduced as the digestion of the connectin progressed; the rate of reduction of active tension was larger than that of resting tension. Maximum shortening speed and calcium ion sensitivity of active tension were not changed by the digestion. Electron micrographs showed that A-bands in the fibers treated with trypsin are dislocated from I-bands. These results suggest that the digestion of connectin does not directly influence the reaction of actin-myosin-regulatory proteins, and thus the resultant reduction in the active tension is mainly due to disordering of the regular structure in a sarcomere.
Higuchi
H
H
Department of Physiology, Jikei University School of Medicine, Tokyo.
D000818:Animals; D064211:Connectin; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D009119:Muscle Contraction / Q000502:physiology*; D009124:Muscle Proteins / Q000502:physiology*; D009132:Muscles / Q000378:metabolism; D011494:Protein Kinases; D011892:Rana catesbeiana; D014357:Trypsin / Q000008:administration & dosage
D064211:Connectin; D009124:Muscle Proteins; D011494:Protein Kinases; D014357:Trypsin