Féliciangéli Sylvain, Kitabgi Patrick
Institut de Pharmacologie Moléculaire et Cellulaire, CNRS-UMR 6097, 660 Route des Lucioles, 06560 Valbonne, France.
Biochem Biophys Res Commun. 2002 Jan 11;290(1):191-6. doi: 10.1006/bbrc.2001.6137.
The mechanisms for sorting proteins to the regulated secretory pathway (RSP) remains poorly understood. We recently reported that dibasic sequences that are cleaved by pro-protein convertases (PCs) in pro-neurotensin also acted as sorting signal for the precursor. Here we addressed two questions regarding the role of dibasics as sorting signal: (i) Are dibasics sufficient to direct proteins to the RSP? (ii) Do they sort proteins by virtue of their interaction with PCs? The first question was studied by inserting dibasics in beta-lactamase, a constitutively secreted protein and comparing the regulated secretion of beta-lactamase to that of its mutant in transfected endocrine cells. The second question was investigated by comparing the regulated release of pro-neurotensin in PC12 cells that are devoid of PCs to that in PC1- and PC2-transfected PC12 cells. The data show that the mutant beta-lactamase was indeed targeted in part to the RSP and that pro-neurotensin was sorted to the RSP without the assistance of the PCs, thus indicating that dibasics can act as sorting signal by themselves independently of their interaction with PCs.
蛋白质分选进入调节性分泌途径（RSP）的机制仍未得到充分了解。我们最近报道，在神经降压素原中被前体蛋白转化酶（PCs）切割的双碱性序列也作为前体的分选信号。在此，我们针对双碱性序列作为分选信号的作用提出了两个问题：（i）双碱性序列是否足以将蛋白质导向RSP？（ii）它们是否通过与PCs的相互作用对蛋白质进行分选？第一个问题通过将双碱性序列插入β-内酰胺酶（一种组成性分泌蛋白）中进行研究，并比较转染的内分泌细胞中β-内酰胺酶与其突变体的调节性分泌。第二个问题通过比较缺乏PCs的PC12细胞与转染了PC1和PC2的PC12细胞中神经降压素原的调节性释放来研究。数据表明，突变的β-内酰胺酶确实部分靶向RSP，并且神经降压素原在没有PCs协助的情况下被分选到RSP，因此表明双碱性序列可以独立于其与PCs的相互作用而自身作为分选信号发挥作用。
