Calpastatin expression in porcine cardiac and skeletal muscle and partial gene structure.
The expression in porcine skeletal and cardiac muscle of calpastatin, the specific endogenous inhibitor of the calpain proteolytic system, was examined 16 h after a single dose of a specific beta(2)-agonist. Immunoblotting of extracts indicated that treatment increased skeletal calpastatin 135-kDa band intensity (P < 0.01), while in cardiac combined 145- and 135-kDa band intensity decreased (P < 0.05). Treatment increased skeletal (P < 0.01) but not cardiac calpastatin mRNA steady-state levels. Three types of cardiac calpastatin mRNA transcripts were identified by 5'-RACE. Types I and II encoded a putative XL region that originated either from exon 1x(A) or exon 1x(B), arranged in tandem. Type III predominated in skeletal muscle and originated from exon 1u, which was located 40-50 kb 3' to exons 1x(A) and 1x(B). The region 5' to exon 1u may act as an independent promoter regulated by a cAMP-dependent mechanisms, thereby explaining the differential response of calpastatin to adrenergic stimulation in cardiac and skeletal muscle.
Parr
T
T
Division of Nutritional Biochemistry, University of Nottingham, Loughborough, Leicestershire, LE12 5RD, United Kingdom. tim.parr@nottingham.ac.uk
Sensky
P L
PL
Bardsley
R G
RG
Buttery
P J
PJ
D024506:5' Flanking Region; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics*; D002154:Calpain / Q000037:antagonists & inhibitors; D002976:Clenbuterol / Q000494:pharmacology; D005091:Exons / Q000235:genetics; D015151:Immunoblotting; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013552:Swine
D000318:Adrenergic beta-Agonists; D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; C033668:calpastatin; D002154:Calpain; D002976:Clenbuterol