ИСТИНА

HspB7 belongs to the large family of small heat shock proteins forming the first line of stress defense controlling cell proteostasis. HspB7 is selectively expressed in cardiac and skeletal muscles and in adipocytes. Although this protein was described more than twenty years ago, many properties of HspB7 remain poorly characterized. Therefore, by using affinity chromatography on immobilized antiHspB7 antibodies we obtained human cardiac HspB7 (tissue HspB7, tHspB7) and recombinant HspB7(rHspB7) expressed E. coli. In contrast to its recombinant counterpart, tHspB7 is acetylated on the Nterminal Ser and does not contain any other posttranslational modifications. We also analyzed expression of different small heat shock proteins (HspB1, HspB5, HspB6 and HspB8) in human heart and have found that the level of HspB7 expression is about 10 times lower than that of HspB1. Since HspB7 is predominantly expressed in skeletal and heart muscle it was supposed that this protein can somehow modulate assembly of actin filaments. In agreement with the earlier published data we found that in dotblot rHspB7 interact with actin. However, cosedimention failed to reveal specific interaction of rHspB7 with Factin or Factin decorated by tropomyosin. The data of intrinsic fluorescence and native gel electrophoresis indicated that rHspB7 does not interact with Gactin and does not affect heat induced aggregation of either Gor Factin. Comparison of the structure and properties of tHspB7 and rHspB7 requires further detailed investigation. Acknowledgement. This investigation has been supported by Russian Science Foundation (grant N 207400013 to L.K.M). This research has been supported by the Interdisciplinary Scientific and Educational School of Moscow University "Molecular Technologies of the Living Systems and Synthetic Biology".