Dilaver Gönül, van de Vorstenbosch Rinske, Tárrega Céline, Ríos Pablo, Pulido Rafael, van Aerde Karlijn, Fransen Jack, Hendriks Wiljan
Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, the Netherlands.
FEBS J. 2007 Jan;274(1):96-108. doi: 10.1111/j.1742-4658.2006.05568.x. Epub 2006 Nov 27.
The single-copy mouse gene Ptprr gives rise to different protein tyrosine phosphatase (PTP) isoforms in neuronal cells through the use of distinct promoters, alternative splicing, and multiple translation initiation sites. Here, we examined the array of post-translational modifications imposed on the PTPRR protein isoforms PTPBR7, PTP-SL, PTPPBSgamma42 and PTPPBSgamma37, which have distinct N-terminal segments and localize to different parts of the cell. All isoforms were found to be short-lived, constitutively phosphorylated proteins. In addition, the transmembrane isoform, PTPBR7, was subject to N-terminal proteolytic processing, in between amino acid position 136 and 137, resulting in an additional, 65-kDa transmembrane PTPRR isoform. Unlike for some other receptor-type PTPs, the proteolytically produced N-terminal ectodomain does not remain associated with this PTPRR-65. Shedding of PTPBR7-derived polypeptides at the cell surface further adds to the molecular complexity of PTPRR biology.
单拷贝小鼠基因Ptprr通过使用不同的启动子、可变剪接和多个翻译起始位点，在神经元细胞中产生不同的蛋白酪氨酸磷酸酶（PTP）异构体。在此，我们研究了施加于PTPRR蛋白异构体PTPBR7、PTP-SL、PTPPBSgamma42和PTPPBSgamma37的一系列翻译后修饰，这些异构体具有不同的N端片段，并定位于细胞的不同部位。所有异构体均被发现是寿命短暂的组成型磷酸化蛋白。此外，跨膜异构体PTPBR7在氨基酸位置136和137之间经历N端蛋白水解加工，产生一种额外的65 kDa跨膜PTPRR异构体。与其他一些受体型PTP不同，蛋白水解产生的N端胞外域并不与这种PTPRR-65保持关联。PTPBR7衍生多肽在细胞表面的脱落进一步增加了PTPRR生物学的分子复杂性。
