Ubiquitination precedes internalization and proteolytic cleavage of plasma membrane-bound glycine receptors
Ubiquitination precedes internalization and proteolytic cleavage of plasma membrane-bound glycine receptors
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DOI：
10.1074/jbc.m102121200
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发表时间：
2001-11-16
影响因子：
4.8
通讯作者：
Schmalzing, G
中科院分区：
文献类型：
--
作者：
Büttner, C;Sadtler, S;Schmalzing, G
发育中的脊髓神经元中的抑制性甘氨酸受体（GlyR）在拮抗剂抑制后被有效内化。在这里，我们使用表面标记结合亲和纯化，以显示在非洲爪蟾卵母细胞中产生的homopentameric α 1 GlyRs的蛋白水解切口成35和13 kDa的片段后，长期孵育。有缺口的GlyR不存在于细胞表面，表明蛋白水解只发生在胞吞途径中。与这种解释一致，溶酶体pH升高，而不是蛋白酶体抑制剂lactacystin，阻止GlyR裂解。在内化之前，al GlyR与质膜中的泛素广泛缀合。我们的研究结果是一致的泛素化调节胞吞作用和随后的蛋白水解的GlyRs驻留在质膜上。因此，泛素结合酶可能通过决定突触后受体的数量在突触可塑性中起着至关重要的作用。
The inhibitory glycine receptor (GlyR) in developing spinal neurones is internalized efficiently upon antagonist inhibition. Here we used surface labeling combined with affinity purification to show that homopentameric alpha1 GlyRs generated in Xenopus oocytes are proteolytically nicked into fragments of 35 and 13 kDa upon prolonged incubation. Nicked GlyRs do not exist at the cell surface, indicating that proteolysis occurs exclusively in the endocytotic pathway. Consistent with this interpretation, elevation of the lysosomal pH, but not the proteasome inhibitor lactacystin, prevents GlyR cleavage. Prior to internalization, al GlyRs are conjugated extensively with ubiquitin in the plasma membrane. Our results are consistent with ubiquitination regulating the endocytosis and subsequent proteolysis of GlyRs residing in the plasma membrane. Ubiquitin-conjugating enzymes thus may have a crucial role in synaptic plasticity by determining postsynaptic receptor numbers.