Proteolysis of myosin and troponin in human myocardium of elderly subjects.
Actomyosin was prepared from human myocardium and its protein composition was examined by SDS-polyacrylamide gel electrophoresis. For some preparations, particularly actomyosin isolated from elderly subjects, a high molecular weight (HMW) band (identified as a breakdown product of myosin heavy chain) appeared, while the troponin-T subunit decreased. Myofibril associated protease (MFP) activity showed no significant difference as a function of proteolysis. In agreement with the proteolysis of troponin-T and myosin, the Ca2+ sensitivity of Mg2(+)-ATPase activity decreased while the extent of the stimulation of Ca2(+)-ATPase by N-ethylmaleimide remained unchanged. This type of proteolysis would affect the Ca2(+)-dependent regulation of muscle contraction but not the contractility per se.
Yoshida
K
K
Department of Legal Medicine, Osaka University Medical School, Japan.
Hanafusa
T
T
Matoba
R
R
Wakasugi
C
C
D000205:Actomyosin / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002102:Cadaver; D002154:Calpain / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007223:Infant; D008875:Middle Aged; D008970:Molecular Weight; D009206:Myocardium / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
D014336:Troponin; D000205:Actomyosin; D010447:Peptide Hydrolases; D002154:Calpain; D009218:Myosins