Functional differences between two major ubiquitin receptors in the proteasome; S5a and hRpn13

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• 作者：Muthukumar Elangovan ; Choongseob Oh ; Lavanya Sukumaran ; Cezary Wó ; jcik ; Yung Joon Yoo
• 关键词：Proteasome ; Rpn13 ; S5a ; Ubiquitin receptor
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2010
• 出版时间：28 May 2010
• 年：2010
• 卷：396
• 期：2
• 页码：425-428
• 全文大小：622 K

文摘

It is well known that S5a and hRpn13 are two major ubiquitin (Ub) receptors in the proteasome but little is known about their functional difference in recruiting ubiquitinated substrates. In this study using siRNA-mediated knockdown of S5a or hRpn13, we found that two Ub receptors had different substrate specificity although similar level of accumulation of high molecular weight Ub-conjugates was observed. Interesting enough, depletion of S5a, but not hRpn13, resulted in the Ub-containing aggregates and induced ER chaperones such as Grp78 and Grp94. ERAD substrates such as α-TCR and α1-antitrypsin were also stabilized by the depletion of S5a but not hRpn13. Our results suggest that there is different substrate specificity between S5a and hRpn13 at the level of delivery and S5a may be the major docking site for ERAD substrates.