|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1994 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1993 : ¥1,500,000 (Direct Cost : ¥1,500,000)
In animal cells, secretary and membrane proteins were de novo synthesized and folded in endoplasmic reticulum. Among them, the abnormal structure proteins such as mutant, misfolded and nonassociated polypeptides are segregated from the normal proteins, retained and finally degraded in the endoplasmic reticulum (quality control) . Although many molecular elements, involved in the quality control of nascent polypeptides in the endoplasmic reticulum, have been identified, protease (s) , which acts on the degradation of abnormal proteins, is not clear. In this study, novel proteases, which are candidates for members of quality control machinery, were purified from the endoplasmic reticulum of rat liver and named ER-60 protease and ER-72 protease. These were shown to be cysteine proteases which have unusual substrate specificity and sensitivities to protease inhibitors. cDNAs of rat and human ER-60 protease were cloned and sequenced. From these cDNAs, large expression systems of recombinant proteins in E.coli were established. A crystallization of recombinant ER-60 protease for X-ray analysis was tried and some conditions, that protein crystals were formed, were found. Experimental systems established in this study might be useful tools for the determination of relationships between structure and regulation of novel cysteine proteases of endoplasmic reticulum in future.