Enhancement of Ca2+-induced Ca2+ release in calpain treated rabbit skinned muscle fibers.
Calpain treatment of rabbit skinned muscle fibers resulted in proteolysis of junctional foot protein or Ca2+ release channel of the sarcoplasmic reticulum. Electrophoretic and immunoblot analyses indicate that calpain cleaves off approximately 130 kDa peptide from the N-terminus. After such treatment, Ca2+ capacity of the sarcoplasmic reticulum remained normal and both Ca2+ and adenine nucleotide dependence of Ca2+-induced Ca2+ release mechanism were retained. However, the Ca2+-activated Ca2+ release rate was increased by two fold after the proteolysis. The results suggest the presence of functional domains in the junctional foot protein, and the N-terminus domain controls the activity of the Ca2+ channel without changing Ca2+ and nucleotide sensitivities.
Iino
M
M
Department of Pharmacology, Faculty of Medicine, University of Tokyo, Japan.
Takano-Ohmuro
H
H
Kawana
Y
Y
Endo
M
M
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002154:Calpain / Q000494:pharmacology*; D066298:In Vitro Techniques; D008970:Molecular Weight; D009124:Muscle Proteins / Q000502:physiology*; D009132:Muscles / Q000187:drug effects; D010446:Peptide Fragments / Q000737:chemistry; D011817:Rabbits; D011950:Receptors, Cholinergic / Q000737:chemistry / Q000502:physiology*; D019837:Ryanodine Receptor Calcium Release Channel; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013329:Structure-Activity Relationship
D015220:Calcium Channels; D009124:Muscle Proteins; D010446:Peptide Fragments; D011950:Receptors, Cholinergic; D019837:Ryanodine Receptor Calcium Release Channel; D002154:Calpain; D002118:Calcium