Ca 2+ -specific removal of Z lines from rabbit skeletal muscle.
J Cell Biol
; 52(2): 367-81, 1972 Feb.
Article
em En
| MEDLINE
| ID: mdl-4621650
ABSTRACT
Removal of rabbit psoas strips immediately after death and incubation in a saline solution containing 1 mM Ca(2+) and 5 nM Mg(2+) for 9 hr at 37 degrees C and pH 7.1 causes complete Z-line removal but has no ultrastructurally detectable effect on other parts of the myofibril. Z lines remain ultrastructurally intact if 1 mM 1,2-bis-(2-dicarboxymethylaminoethoxy)-ethane (EGTA) is substituted for 1 mM Ca(2+) and the other conditions remain unchanged. Z lines are broadened and amorphous but are still present after incubation for 9 hr at 37 degrees C if 1 mM ethylenediaminetetraacetate (EDTA) is substituted for 1 mM Ca(2+) and 5 mM Mg(2+) in the saline solution. A protein fraction that causes Z-line removal from myofibrils in the presence of Ca(2+) at pH 7.0 can be isolated by extraction of ground muscle with 4 mM EDTA at pH 7.0-7.6 followed by isoelectric precipitation and fractionation between 0 and 40% ammonium sulfate saturation. Z-line removal by this protein fraction requires Ca(2+) levels higher than 0.1 mM, but Z lines are removed without causing any other ultrastructurally detectable degradation of the myofibril. This is the first report of a protein endogenous to muscle that is able to catalyze degradation of the myofibril. The very low level of unbound Ca(2+) in muscle cells in vivo may regulate activity of this protein fraction, or alternatively, this protein fraction may be localized in lysosomes.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Extratos de Tecidos
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Cálcio
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Magnésio
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Músculos
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Miofibrilas
Limite:
Animals
Idioma:
En
Revista:
J Cell Biol
Ano de publicação:
1972
Tipo de documento:
Article