Characteristics of Thick Filament Assembly of Myoid Cell Myosin

GOMEZ L; FERNANDEZ D; LOPEZ LA

Congreso; XX Reunión Científica Anual 2002, Sociedad de Biología de Cuyo; 2002

Peritubular myoid cells contain abundant actin filaments and they are contractile. Previously, we have show that rat myoid cells contain an isotype of smooth muscle myosin which is not assembled in filaments. In order to determine whether this myosin isotype is able to assemble in vitro, myosin of rat myoid cells was purified and it´s salt-dependent solubility was assessed in a buffer containing different concentrations of NaCl. 200 µg/ml of myosin in phosphate-buffered 350 mM NaCl were dialyzed for 12 h again 100-350 mM NaCl. The samples where centrifuged, the pellets and supernatants analyzed by 7.5% SDS-PAGE, and the fraction of assembled myosin quantified by comparison of staining intensity of the bands. The assay showed that 95% of the myosin in 100 and 150 mM NaCl was assembled in filaments, 50% in 200 mM NaCl, and 10% in 350 mM NaCl. These results indicates that myoid cell myosin is able to assemble in vitro in a similar manner to other smooth muscle myosin II isotypes.