Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.54 (calpain 3)
 430 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tenderization of skeletal muscle in meat animals has been closely linked to the postmortem activity of the calpain proteolytic enzyme system, which includes the specific inhibitor calpastatin. Increased understanding of the skeletal muscle-specific calpain isoform p94 has prompted suggestions as to whether it too could have a role in the tenderization process. In this study, two groups of pigs were identified in which shear force measurements after 8 d of conditioning indicated a large variation in the tenderness of longissimus muscle. The quantity of p94 in the muscle was monitored by immunoblotting, using a porcine-specific polyclonal antibody raised against a recombinant peptide fragment generated as a fusion protein. The antiserum recognized a 94-kDa protein associated with myofibrils in skeletal but not cardiac muscle, as expected for this calpain isoform, although it could not be tested with the native protein because of the extreme instability of p94. In the first experiment, the mean shear force for the tough group was 6.71 +/- .28 kg (n = 12, SEM) and that of the tender group was 3.87 +/- .12 kg (n = 12), but there was no difference in the normalized absorbance of the immunopositive 94 kDa band on Western blots from samples collected at approximately 40 min postmortem. In the second experiment, the stability of p94 in chilled carcasses was investigated over 24 h, using a further two groups of 10 tough and 10 tender pigs of mean shear force values 5.36 +/- .14 kg and 2.81 +/- .15 kg, respectively. In tough and tender animals, there was a decline (P < .05) in the 94-kDa immunostaining material of mean half-lives of 13.8 and 12.9 h, respectively, although there was considerable variability. Despite this variability in half lives and shear force values, no correlation was seen between these factors. Thus, in porcine longissimus muscle, the variability in tenderness after 8 d of conditioning cannot be attributed to an underlying variability in p94.
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PMID:Relationship between skeletal muscle-specific calpain and tenderness of conditioned porcine longissimus muscle. 1022 62

Muscular dystrophy with myositis (mdm) is a recessive mouse mutation that is caused by a small deletion in the giant elastic muscle protein titin. Homozygous mdm/mdm mice develop a progressive muscular dystrophy, leading to death at approximately 2 months of age. We surveyed the transcriptomes of skeletal muscles from 24 day old homozygous mdm/mdm and +/+ wild-type mice, an age when MDM animals have normal passive and active tensions and sarcomeric structure. Of the 12488 genes surveyed (U74 affymetrix array), 75 genes were twofold to 30-fold differentially expressed, including CARP (cardiac ankyrin repeat protein), ankrd2/Arpp (a CARP-like protein) and MLP (muscle LIM protein), all of which associate with the titin filament system. The four genes most strongly affected (eightfold to 30-fold change) were all members of the CARP-regulated Nkx-2.5-dependent signal pathway, and CARP mRNA level was 30-fold elevated in MDM skeletal muscle tissues. The CARP protein overexpressed in MDM became associated with the I-band region of the sarcomere. The mdm mutation excises the C-terminal portion of titin's N2A region, abolishing its interaction with p94/calpain-3 protease. Thus, the composition of the titin N2A protein complex is altered in MDM by incorporation of CARP and loss of p94/calpain-3. These changes were absent from the following control tissues (1). cardiac muscles from homozygous mdm/mdm animals, (2). skeletal and cardiac muscle from heterozygous mdm/+ animals, and (3). dystrophic muscles from MDX mice. Thus, the altered composition of the titin N2A complex is specific for the titin-based skeletal muscular dystrophy in MDM.
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PMID:Induction and myofibrillar targeting of CARP, and suppression of the Nkx2.5 pathway in the MDM mouse with impaired titin-based signaling. 1474 Dec 10