It has long been proposed that Leukocyte common Antigen-Related Receptor Protein Tyrosine Phosphatases (LAR-RPTPs) are cell-adhesion proteins for the control of synapse assembly. Their synaptic nanoscale localization, however, has not been established, and the fine structure of synapses after knockout of the three vertebrate genes for LAR-RPTPs (PTPδ, PTPσ and LAR) has not been tested. Here, we find that PTPδ is precisely apposed to postsynaptic scaffolds at excitatory and inhibitory synapses using superresolution microscopy. We generated triple-conditional knockout mice for PTPδ, PTPσ and LAR to test whether they are essential for synapse structure. While mild effects on synaptic vesicle clustering and active zone architecture were detected, synapse numbers and their overall structure were unaffected, membrane anchoring of the active zone persisted, and vesicle docking and release were normal. We conclude that LAR-RPTPs, despite their localization at synaptic appositions, are dispensable for the organization and function of presynaptic nerve terminals.

中文翻译：

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联合敲除PTPδ，PTPσ和LAR后的完整突触结构和功能

长期以来，人们一直认为白细胞常见的抗原相关受体蛋白酪氨酸磷酸酶（LAR-RPTPs）是用于控制突触装配的细胞粘附蛋白。然而，它们的突触纳米级定位尚未建立，并且尚未测试敲除LAR-RPTP的三个脊椎动物基因（PTPδ，PTPσ和LAR）后突触的精细结构。在这里，我们发现使用超高分辨率显微镜将PTPδ精确地置于兴奋性和抑制性突触的突触后支架上。我们为PTPδ，PTPσ和LAR生成了三条件敲除小鼠，以测试它们是否对突触结构必不可少。虽然检测到对突触小泡聚集和活动区结构的轻微影响，但突触数量及其整体结构并未受到影响，活性区的膜锚固持续，并且囊泡对接和释放正常。我们得出的结论是，尽管LAR-RPTP位于突触并置，但对于突触前神经末梢的组织和功能却是必不可少的。