Removal of Z-lines and alpha-actinin from isolated myofibrils by a calcium-activated neutral protease
| Autor: | D A Fischman, Murray Rabinowitz, M K Reddy, J D Etlinger, R Zak |
|---|---|
| Rok vydání: | 1975 |
| Předmět: |
biology
Chemistry ATPase Skeletal muscle macromolecular substances Cell Biology musculoskeletal system Trypsin Biochemistry EGTA chemistry.chemical_compound Actinin alpha 1 medicine.anatomical_structure Casein medicine biology.protein Myofibril Molecular Biology Polyacrylamide gel electrophoresis medicine.drug |
| Zdroj: | Journal of Biological Chemistry. 250:4278-4284 |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/s0021-9258(19)41414-2 |
| Popis: | A calcium-activated factor (CaAF) has been isolated and partially purified from the post-myofibrillar supernatant fraction of rabbit skeletal muscle. The 200-fold purified CaAF hydrolyzed denatured casein, [3-H]acetyl hemoglobin, and N-ethyl[3-H]maleimide-labeled alpha-actinin. The proteolytic activity has a pH optimum at 6.9 and is dependent on the presence of Ca2+ (optimum concentration, 10 mM). Digestion of isolated myofibrils with CaAF results in removal of Z-lines and in a parallel loss of a 90, 000-dalton protein that has a mobility identical with that of alpha-actinin as determined by polyacrylamide gel electrophoresis. A protein with the properties of alpha-actinin (identical electrophoretic mobility, and ability to accelerate the Mg2+-activated ATPase of reconstituted actomyosin) was isolated from the supernatant of CaAF-treated myofibrils. The release of alpha-actinin from myofibrils by the calcium-activated neutral protease occurs in the absence of detectable change in the electrophoretic profiles of the other myofibrillar proteins, or in the ethylene glycol bis(beta-aminoethyl ether)-N, N' tetraacetic acid (EGTA) sensitivity of Mg2+-activated ATPase. In contrast to the specific removal of Z-lines and of alpha-actinin by CaAF, trypsin treatment of myofibrils results in extensive degradation of myosin heavy chains and of the inhibitory component of troponin (TN-I), and in loss of EGTA sensitivity of myofibrillar ATPase. The degradation of TN-I and loss of EGTA sensitivity occur before the Z-line disappearance. |
| Databáze: | OpenAIRE |
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