ISOLATION OF TROPOMYOSIN PARTICLES FROM THE CYTOSOL OF CULTURED CELLS
AND THEIR PROTEIN COMPOSITION ANALYSIS
D.E. Bobkov,1 A.A. Aisenstadt,1 I.V. Kropacheva,1 G.P. Pinaev 1,2
1 Institute of Cytology RAS, St. Petersburg, and 2 Faculty of Biomedical Physics and Bioengineering,
St. Petersburg State Polytechnic University;
e-mail: bobkovde@yandex.ru
The presence of actin-binding protein, tropomyosin, shaped as particles or protein complexes that have no
bonds with actin structures were found while the analisys of structural rearrangements of actin cytoskeleton. However,
their functioning is still unknown. To study the composition and properties of these protein complexes a
novel method of their separation from the cells without destroying the structures of the cytoskeleton have been
developed. The protein composition of isolated tropomyosin particles has been analised by gel filtration, electrophoresis
and Western blotting. They appeared to be a multimolecular complexes of about 700 kDa. Beside
the tropomyosin and actin these complexes also contain the Hsp70, Hsp90 and myosin-9 identified by mass
spectrometry analisys. Also, under ingibition of deacetylases by trichostatin A, changes in the number of particles
and redistribution of tropomyosin between cytosol and cytoskeleton take place along with actin cytoskeleton
rearrangements. The results obtained give a reason to assume that these multimolecular complexes may participate
in the process of reorganization of the actin microfilaments.
Key words: tropomyosin, protein complexes, actin cytoskeleton, myosin-9, heat shock proteins
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