SELECTIVE EFFECT OF EOF ON THE ENDORIBONUCLEASE ACTIVITY OF DIFFERENT SUBPOPULATIONS
OF 26S PROTEASOMES FROM A431 CELLS. SPECIFITY OF EXTRACELLULAR PROTEASOME POPULATION
V. A. Kulichkova, A. G. Mittenberg, I. N. Evteeva, M. V. Toktarova, A. S. Tsimokha, I. V. Volkova,
Yu. B. Ermolaeva, L. N. Cause, I. M. Konstantinova 1
Institute of Cytology RAS, St. Petersburg, Russia;
1 e-mail: ikonst@mail.cytspb.rssi.ru
For the first time, it has been shown that population of proteasomes is heterogeneous in their RNAse activity.
EOF exerts selective effect on different subpopulations of proteasomes. The RNAse activity of cytoplasmic proteasomes is induced
under the influence of EGF on epidermoid carcinoma cell line A431. However, the activity of proteasomes isolated from culture medium
and of nuclear proteasomes is inhibited by EGF. The above enzymatic activity has been shown to be specifically and selectively
dependent on phosphorylation of proteaso-mal subunits in different subpopulations of proteasomes. Proteasome involvement in
the coordinated control of specific messenger RNA molecules stability is suggested, and one of the mechanisms of this control
might be an export of specific subpopulation of proteasomes from the cell.
Key words: proteasomes, mRNA, stability, ribonucleases, epidermal growth factor
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