ISSN:
0263-6484
Schlagwort(e):
myosin heavy chain isozyme
;
cultured cardiac myocyte
;
thyroxine
;
immunoelectron microscopy
;
enzyme-labelled antibody
;
monoclonal antibody
;
myofilament
;
polyribosome
;
Chemistry
;
Biochemistry and Biotechnology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Medizin
Notizen:
To investigate how newly synthesized cardiac myosins are assembled into myofilaments, we analysed the distribution of newly produced α-myosin heavy chain isozyme in sarcomeres by immunoelectron microscopy using a monoclonal antibody (CMA19), which is specific for α-myosin heavy chain. Isozymic changes in myosin heavy chains from β to α type were induced in canine ventricular muscles and cultured ventricular myocytes by administration of 1-thyroxine. We incubated the glycerinated ventricular muscles or cultured ventricular myocytes with the enzyme (horseradish peroxidase) labelled Fab fragment of CMA19. After the reaction with 3, 3′-diaminobenzidine and osmification, we prepared ultrathin sections of the ventricular muscles or cultured ventricular myocytes and analysed their staining patterns by electron microscopy.There was apparent heterogeneity in the staining intensity of the myofilaments among different cells, among different myofibrils and even intramyofibrillarly. Higher magnification revealed that there were scattered foci of strong reaction which appeared to be foci of assembly of the newly synthesized α-myosin heavy chain. Immunocytochemical study also showed heterogeneous reactions within myofilaments and that there were scattered foci of myofilament assembly, which were closely associated with polyribosomes producing newly induced α-myosin heavy chain. These data suggest that newly synthesized cardiac myosins are assembled into myofilaments from the sites of synthesis, that is polyribosomes. This may explain the heterogeneity of the assembly pattern of newly synthesized cardiac myosins at the subcellular level.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cbf.290080206
Permalink
