The BTB/kelch protein, KRIP6, modulates the interaction of PICK1 with GluR6 kainate receptors

Abstract

Neuronal proteins of the BTB/kelch and PDZ domain families interact with different regions of the cytoplasmic C-terminal domain of the GluR6 kainate receptor subunit. The BTB/kelch protein KRIP6 binds within a 58 amino acid segment of GluR6 proximal to the plasma membrane. In contrast, PDZ domain proteins, such as PICK1 and PSD95, interact with the last 4 residues of the GluR6 C-terminus. KRIP6 reduces peak currents mediated by recombinant GluR6 receptors and by native kainate receptors in neurons, whereas PICK1 stabilizes kainate receptors at synapses. Thus, protein-protein interactions at the C-terminal domain of GluR6 are important for regulating kainate receptor physiology. Here, we show by co-clustering and co-immunoprecipitation that KRIP6 interacts with PICK1 in heterologous cells. In addition, we demonstrate a novel modulation of GluR6 receptors by PICK1 resulting in increased peak current and relative desensitization of GluR6-mediated currents, phenotypes opposite to those produced by KRIP6. Importantly, these effects cancel out when KRIP6 and PICK1 are co-expressed together with GluR6. KRIP6 and PICK1 strongly co-cluster and coimmunoprecipitate regardless of the presence of GluR6. Immunofluorescence analysis reveals that GluR6 can either join the KRIP6-PICK1 clusters or remain separate; however, co-expression of KRIP6 reduces the fraction of PICK1 that co-immunoprecipitates with GluR6. Taken together, these results indicate that, in addition to a previously demonstrated direct interaction with the GluR6 Cterminal domain, KRIP6 regulates kainate receptors by inhibiting PICK1 modulation via competition or a mutual blocking effect.

Selective Proteasomal Degradation of the B′β Subunit of Protein Phosphatase 2A by the E3 Ubiquitin Ligase Adaptor Kelch-like 15

“…KLHL15 belongs to a large family of proteins with a characteristic domain architecture consisting of an N-terminal BTB (broadcomplex, tram track, and bric-a-brac) domain, a C-terminal Kelch ␤-propeller, and a middle BACK (between BTB and C-terminal Kelch) domain (13,14). Several KLHL proteins have been shown to bridge Cul3-containing E3 ligases to specific substrates (15)(16)(17)(18)(19)(20)(21). Here we report on the characterization of the KLHL15-Cul3 complex as a B subunit-specific regulator of PP2A.…”

Subunit-specific desensitization of heteromeric kainate receptors

“…1). This could result if cultured neurons had a different combination of GluK1/3 and GluK4/5 subunits than GluK2/GluK4 or from modulation of heteromeric receptor function by natively expressed auxiliary proteins (Hirbec et al 2003; Laezza et al 2008; Zhang et al 2009).…”

The Notch ligand E3 ligase, Mind Bomb1, regulates glutamate receptor localization in Drosophila

“…These data suggest that most regulatory proteins promote the trafficking and localization of GluRIIA-containing receptors. Indeed, the PSD proteins KRIP6 and S-SCAM have been shown to be important for the membrane localization of the Kainate receptor subunit GluR6 and the AMPA receptor subunit GluA2 (Laezza et al , 2008; Danielson et al , 2012). Mutations in the Drosophila orthologs diablo ( dbo ) and magi produce a significant reduction in the synaptic localization of GluRIIA (Fig.…”