Regulation of synaptic plasticity by receptor-like protein tyrosine phosphatase

Ptprz的细胞外区域被MMP-9或纤溶酶脱落，产生其膜系片段。据报道，当突触重塑发生时，这两种蛋白酶都被激活。我们发现Ptprz片段在突触后密度PSD部分中积累，表明该受体实际上在中央突触处被裂解。我们确定了Git 1和Magi 1的去磷酸化位点。在这些底物蛋白中的目标磷酸酪氨酸残基周围的主要序列的比对显示出相当大的相似性，这表明Ptprz的底物识别的共识基序。我们发现，由此推断的底物基序存在于一些蛋白质，包括在桩蛋白的Tyr 118。最后，我们验证了Ptprz在培养的细胞中在该位点有效地使桩蛋白去磷酸化。

The extracellular region of Ptprz is shedded by MMP-9 or plasmin, producing its membrane-tethered fragment. Both proteases are reportedly activated when synaptic remodeling is occurring. We revealed that Ptprz fragments are accumulated in the post synaptic density PSD fraction, indicating that this receptor is actually cleaved at central synapses. We identified the dephosphorylation sites in Git1 and Magi1. Alignment of the primary sequences surrounding the target phospho-tyrosine residue in these substrate proteins showed a considerable similarity, suggesting a consensus motif for substrate recognition by Ptprz. We found that the substrate motif thus deduced is present in some proteins, including at Tyr118 of paxillin. Finally, we verified that Ptprz efficiently dephosphorylates paxillin at this site in cultured cells.