HYPERTHYREOSIS INHIBITS THE ABILITY OF ACTIN TO FORM STRONG-BINDING WITH MYOSIN
V. P. Kirillina,1,* A. Jakubiec-Puka,2 Yu. S. Borovikov 1
1 Institute of Cytology RAS, St. Petersburg, Russia,
and 2 Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland;
*e-mail: kirill@mail.cytspb.rssi.ru
The effect of hyperthyreosis development induced by the increase in thyroid hormones in rats (during
2—4 weeks) on the orientation and mobility of fluorescent probe N-(iodoacetyl)-(1-naphtyl-5-sulpho-ethylenediamine)
specifically bound to Cys 374 of actin in ghost muscle fibers isolated from fast (EDL) and slow (SOL)
rat muscles was studied. It was found that the binding of myosin subfragment-1 (S1) to F-actin induced the typical
for the formation of strong binding actomyosin decrease in mobility of actin subdomain 1 and its rotation towards
thin filament periphery. Development of hyperthyreosis markedly inhibited these phenomena. The maximal
effect was observed after 21 days of disease development. It is suggested that one of the reasons of the contractile
deficit of muscle in hyperthyreosis is inhibition of the strong binding between actin and myosin during
ATPase cycle.
Key words: muscle contraction, F-actin, actin conformational changes, hyperthyreosis, polarized fluorescence
| Pdf |
Back |
Contents |
Main |
|
