Norcott J P, Solari R, Cutler D F
Medical Research Council Laboratory for Molecular Cell Biology, University College London, United Kingdom.
J Cell Biol. 1996 Sep;134(5):1229-40. doi: 10.1083/jcb.134.5.1229.
Targeting of P-selectin to the regulated secretory organelles (RSOs) of phaeochromocytoma PC12 cells has been investigated. By expressing from cDNA a chimera composed of HRP and P-selectin, and then following HRP activity through subcellular fractionation, we have discovered that P-selectin contains signals that target HRP to the synaptic-like microvesicles (SLMV) as well as the dense-core granules (DCGs) of these cells. Mutagenesis of the chimera followed by transient expression in PC12 cells shows that at least two different sequences within the carboxy-terminal cytoplasmic tail of P-selectin are necessary, but that neither is sufficient for trafficking to the SLMV. One of these sequences is centred on the 10 amino acids of the membrane-proximal C1 exon that is also implicated in lysosomal targeting. The other sequence needed for trafficking to the SLMV includes the last four amino acids of the protein. The same series of mutations have a different effect on DCG targeting, showing that traffic to the two different RSOs depends on different features within the cytoplasmic domain of P-selectin.
已对嗜铬细胞瘤PC12细胞中P-选择素靶向调节性分泌细胞器（RSO）进行了研究。通过从cDNA表达由HRP和P-选择素组成的嵌合体，然后通过亚细胞分级分离追踪HRP活性，我们发现P-选择素含有将HRP靶向这些细胞的突触样微囊泡（SLMV）以及致密核心颗粒（DCG）的信号。对嵌合体进行诱变，然后在PC12细胞中瞬时表达，结果表明P-选择素羧基末端细胞质尾巴内至少有两个不同的序列是必需的，但单独一个都不足以转运至SLMV。其中一个序列集中在膜近端C1外显子的10个氨基酸上，该外显子也与溶酶体靶向有关。转运至SLMV所需的另一个序列包括该蛋白质的最后四个氨基酸。同一系列的突变对DCG靶向有不同影响，表明转运至两种不同的RSO取决于P-选择素细胞质结构域内的不同特征。
