A mechanism for regulating the strength of synaptic inhibition is enabled by altering the number of GABAA receptors available at the cell surface. Clathrin and adaptor protein 2 (AP2) complex-mediated endocytosis is known to play a fundamental role in regulating cell surface GABAA receptor numbers. Very recently, we have elucidated that phospholipase C-related catalytically inactive protein (PRIP) molecules are involved in the phosphorylation-dependent regulation of the internalization of GABAA receptors through association with receptor β subunits and protein phosphatases. In this study, we examined the implications of PRIP molecules in clathrin-mediated constitutive GABAA receptor endocytosis, independent of phospho-regulation. We performed a constitutive receptor internalization assay using human embryonic kidney 293 (HEK293) cells transiently expressed with GABAA receptor α/β/γ subunits and PRIP. PRIP was internalized together with GABAA receptors, and the process was inhibited by PRIP-binding peptide which blocks PRIP binding to β subunits. The clathrin heavy chain, μ2 and β2 subunits of AP2 and PRIP-1, were complexed with GABAA receptor in brain extract as analyzed by co-immunoprecipitation assay using anti-PRIP-1 and anti-β2/3 GABAA receptor antibody or by pull-down assay using β subunits of GABAA receptor. These results indicate that PRIP is primarily implicated in the constitutive internalization of GABAA receptor that requires clathrin and AP2 protein complex.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience