title: Calpastatin expression in porcine cardiac and skeletal muscle and partial gene structure.
abstract: 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.
authors.affiliation: Division of Nutritional Biochemistry, University of Nottingham, Loughborough, Leicestershire, LE12 5RD, United Kingdom. tim.parr@nottingham.ac.uk
authors.forename: T
authors.initials: T
authors.lastname: Parr
authors.forename: P L
authors.initials: PL
authors.lastname: Sensky
authors.forename: R G
authors.initials: RG
authors.lastname: Bardsley
authors.forename: P J
authors.initials: PJ
authors.lastname: Buttery
mesh_terms: 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
chemical_list: D000318:Adrenergic beta-Agonists; D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; C033668:calpastatin; D002154:Calpain; D002976:Clenbuterol