Phospho-dependent binding of the clathrin AP2 adaptor complex to GABAA receptors regulates the efficacy of inhibitory synaptic transmission
Phospho-dependent binding of the clathrin AP2 adaptor complex to GABAA receptors regulates the efficacy of inhibitory synaptic transmission
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DOI：
10.1073/pnas.0506653102
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发表时间：
2005-10-11
影响因子：
11.1
通讯作者：
Moss, SJ
中科院分区：
文献类型：
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作者：
Kittler, JT;Chen, GJ;Moss, SJ
突触抑制的功效取决于神经元细胞表面表达的γ-氨基丁酸A型受体（GABA(A)Rs）的数量。网格蛋白衔接蛋白 2 (AP2) 复合物是 GABA(A)R 内吞作用以及表面受体数量的关键调节因子。在这里，我们鉴定了一个先前未表征的非典型 AP2 结合基序，该基序保守于所有 GABA(A)R β 亚基亚型的胞内结构域内。该 AP2 结合基序（β 3 亚基中的 KTHLRRRSSQLK）整合了受体 β 亚基内丝氨酸磷酸化的主要位点，该位点内的磷酸化会抑制 AP2 结合。此外，通过使用表面等离子共振，我们确定与 GABA(A)R beta 3 亚基中 AP2 结合基序相对应的肽 (pep beta 3) 仅在去磷酸化时才以高亲和力与 AP2 结合。此外，pep β 3 肽（而非其磷酸化等效物（pep β 3-phos））增强了微型抑制性突触电流和全细胞 GABA(A)R 电流的幅度。 pep beta 3 对 GABA(A)R 电流的这些影响被支持 pep beta 3 对 GABA(A)R 内吞作用的动力依赖性内吞作用抑制剂所阻断。因此，AP2 与 GABA(A)R 结合的磷酸依赖性调节提供了一种机制来指定受体细胞表面数量和抑制性突触传递的功效。
The efficacy of synaptic inhibition depends on the number of gamma-aminobutyric acid type A receptors (GABA(A)Rs) expressed on the cell surface of neurons. The clathrin adaptor protein 2 (AP2) complex is a critical regulator of GABA(A)R endocytosis and, hence, surface receptor number. Here, we identify a previously uncharacterized atypical AP2 binding motif conserved within the intracellular domains of all GABA(A)R beta subunit isoforms. This AP2 binding motif (KTHLRRRSSQLK in the beta 3 subunit) incorporates the major sites of serine phosphorylation within receptor beta subunits, and phosphorylation within this site inhibits AP2 binding. Furthermore, by using surface plasmon resonance, we establish that a peptide (pep beta 3) corresponding to the AP2 binding motif in the GABA(A)R beta 3 subunit binds to AP2 with high affinity only when dephosphorylated. Moreover, the pep beta 3 peptide, but not its phosphorylated equivalent (pep beta 3-phos), enhanced the amplitude of miniature inhibitory synaptic current and whole cell GABA(A)R current. These effects of pep beta 3 on GABA(A)R current were occluded by inhibitors of dynamin-dependent endocytosis supporting an action of pep beta 3 on GABA(A)R endocytosis. Therefore phosphodependent regulation of AP2 binding to GABA(A)Rs provides a mechanism to specify receptor cell surface number and the efficacy of inhibitory synaptic transmission.