The 20S proteasome (prosome) is a highly organized multi-protein compl
ex with approximate molecular weight of about 700 kDa. Whilst the role
of the proteasome in the processing and turnover of cellular proteins
is becoming clearer, its relationship with RNA remains obscure. Over
the last decade the possibility of association of proteasomes with spe
cific RNAs or mRNPs have been particularly controversial. Proteasomes
were reported to inhibit translation of viral mRNAs and to be tightly
associated with RNase activity. It is possible that proteasomes are al
so involved in cellular RNA breakdown and RNA processing like prokaryo
tic RNase E.