Tsubuki S, Kawasaki H, Saito Y, Miyashita N, Inomata M, Kawashima S
Department of Molecular Biology, Tokyo Metropolitan Institute of Medical Science, Japan.
Biochem Biophys Res Commun. 1993 Nov 15;196(3):1195-201. doi: 10.1006/bbrc.1993.2378.
A tripeptide aldehyde protease inhibitor, benzyloxycarbonyl(Z)-Leu-Leu-leucinal (ZLLLa1), initiates neurite outgrowth in PC12 cells at an optimal concentration of 30nM. This result suggests the existence of a protease which regulates neurite formation in PC12 cells. We report here an attempt to identify this target protease in bovine brain using Z-Leu-Leu-Leu-4-methylcoumaryl-7-amide (ZLLL-MCA), in which the aldehyde moiety of ZLLLa1 was changed to 4-methylcoumaryl-7-amide to serve as a substrate for the protease. As a result, we have purified a proteasome with a molecular weight of about 660 kDa as a ZLLL-MCA degrading protease. The activity of the proteasome was inhibited efficiently by ZLLLa1, and was different from known catalytic activities of proteasome in some aspects, suggesting it to be a novel one. Thus, the proteasome may be involved in the regulation of neurite formation in PC12 cells.
一种三肽醛蛋白酶抑制剂，苄氧羰基（Z）-亮氨酰-亮氨酰-亮氨酸醛（ZLLLa1），在30nM的最佳浓度下可诱导PC12细胞的神经突生长。这一结果表明存在一种调节PC12细胞中神经突形成的蛋白酶。我们在此报告了一项尝试，即使用Z-亮氨酰-亮氨酰-亮氨酸-4-甲基香豆素-7-酰胺（ZLLL-MCA）在牛脑中鉴定这种靶蛋白酶，其中ZLLLa1的醛基部分被改为4-甲基香豆素-7-酰胺作为蛋白酶的底物。结果，我们纯化了一种分子量约为660 kDa的蛋白酶体作为ZLLL-MCA降解蛋白酶。该蛋白酶体的活性被ZLLLa1有效抑制，并且在某些方面与已知的蛋白酶体催化活性不同，表明它是一种新型的蛋白酶体。因此，蛋白酶体可能参与了PC12细胞中神经突形成的调节。
