Skeletal muscle-specific calpain, p49: structure and physiological function.
Recent studies indicate that calpain, a cytosolic Ca2+-dependent protease, constitutes a large family comprising ubiquitous, tissue-specific, and atypical calpains. p94 is a homologue of the catalytic large subunit of calpain, expressed predominantly in skeletal muscle. Recently, p94 has been found to interact with connectin/titin, a muscle elastic protein, and its gene has been identified as being responsible for limb-girdle muscular dystrophy type 2A. The loss of function of a calpain species eventually leads to the activation of proteases including other calpain species responsible for muscle degradation. p94 does not form a complex with the small subunit of calpain (30K), but exists as a homodimer. This, together with other results, led us to consider a novel mechanism for the activation of calpain, a Ca2+-induced subunit rearrangement.
Kinbara
K
K
Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
Sorimachi
H
H
Ishiura
S
S
Suzuki
K
K
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002154:Calpain / Q000737:chemistry / Q000502:physiology*; D064211:Connectin; D006801:Humans; D009124:Muscle Proteins / Q000737:chemistry; D018482:Muscle, Skeletal / Q000201:enzymology*; D011494:Protein Kinases / Q000737:chemistry
D064211:Connectin; D009124:Muscle Proteins; C577285:TTN protein, human; D011494:Protein Kinases; D002154:Calpain; D002118:Calcium