RECOMBINANT PROTEASOMAL ALPHA-TYPE SUBUNITS EXHIBIT ENDORIBONUCLEASE ACTIVITY
O. A. Fedorova,1 T. N. Moiseeva, A. G. Mittenberg, N. A. Barlev
Institute of Cytology RAS, St. Petersburg;
1 e-mail: fedorovaolgand@mail.ru
26S proteasome is a multi-subunit protein complex that consists of the regulatory 19S and the catalytic 20S
subcomplexes. The major cellular function of the proteasome is protein degradation. It has been found recently
that the 20S particle, besides its proteolytic activity, also possesses endoribonuclease activity. The latter is mediated
by two α-type subunits (α1 and α5). In this report we have analyzed the remaining α-type subunits for their
ability to hydrolyze RNA. We found that all of the recombinant subunits tested exhibited endoribonuclease activity
which depended on the origin of RNA and the presence of bivalent ions in the reaction. These results indicate
that the endoribonuclease activity of proteasomes may play an important role in cellular metabolism of RNA.
Key words: c-myc, endoribonuclease activity, mRNA, proteasomal α-type subunits, proteasome, p53
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