We have identified two distinct subunits of 20 S proteasomes that are associated with RNase activity. Proteasome subunits zeta and iota, eluted from two-dimensional Western blots, hydrolysed tobacco mosaic virus RNA, whereas none of the other subunits degraded this substrate under the same conditions. Additionally, proteasomes were dissociated by 6 M urea, and subunit zeta, containing the highest RNase activity, was isolated by anion-exchange chromatography and gel filtration. Purified subunit zeta migrated as a single spot on two-dimensional PAGE with a molecular mass of approx. 28 kDa. Addition of anti-(subunit zeta) antibodies led to the co-precipitation of this proteasome subunit and nuclease activity. This is the first evidence that proteasomal α-type subunits are associated with an enzymic activity, and our results provide further evidence that proteasomes may be involved in cellular RNA metabolism.
Involvement of proteasomal subunits zeta and iota in RNA degradation
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Franck PETIT, Anne-Sophie JARROUSSE, Burkhardt DAHLMANN, Axel SOBEK, Klavs B. HENDIL, Jacques BURI, Yves BRIAND, Hans-Peter SCHMID; Involvement of proteasomal subunits zeta and iota in RNA degradation. Biochem J 15 August 1997; 326 (1): 93–98. doi: https://doi.org/10.1042/bj3260093
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