ELKS1 and Ca2+ channel subunit β4 interact and colocalize at cerebellar synapses

Abstract

The cytoskeletal matrix of the active zone (CAZ) and synaptic voltage-dependent calcium channels (VDCCs) are both necessary components for the organization and regulation of synaptic vesicle release. Here we report a novel interaction between the CAZ protein ELKS1b and the VDCC subunit β4 in the molecular layer of the cerebellum. We found that the two proteins co-immunoprecipitated using antibodies against each protein. Using fluorescent immunohistochemistry, we observed colocalization between ELKS1b and VDCC β4 in the molecular layer of the cerebellum, suggesting that these proteins are both present in molecular layer synapses. Analysis of a P/Q-type VDCC knockout mouse (Cacna1a−/−) revealed that the localization of the VDCC β4 subunit to the molecular layer was disrupted, although ELKS1b protein localization was not affected. The results demonstrate that these two proteins interact in vitro and colocalize in the cerebellum, and suggest that their interaction may play a role at the molecular layer synapses of the cerebellum.

Antibody Repertoire in Paraneoplastic Cerebellar Degeneration and Small Cell Lung Cancer

“…We previously identified this immunoreactivity in a patient with SCLC without neurological symptoms suggesting the antibody may be a marker of the underlying SCLC (unpublished). Another patient had an antibody against ELKS1, a protein predominantly expressed in Purkinje cells [18]. Although ELKS1 co-immunoprecipitates with the β4 VGCC subunit, we could not identify antibodies reacting directly with β4 or γ2, which are VGCC subunits that are highly expressed in the cerebellum [18], [19].…”

Rab3 interacting molecule 3 mutations associated with autism alter regulation of voltage-dependent Ca2+ channels

“…It has been revealed that ␤-subunits directly associate with presynaptic proteins including RIMs [18,20,[41][42][43]. RIM proteins are widely distributed in the brain, and abundantly localized at the pre-and post-synapse.…”

The role of laminins in the organization and function of neuromuscular junctions

“…These VGCCs directly interact with synaptic vesicle related proteins syntaxin, synaptosomal associated protein of 25 kDa (SNAP-25), and synaptotagmin, and in turn SNAP-25 and syntaxin modify VGCC function [250–255]. In addition, a number of active zone proteins interact with different subunits of the VGCCs (Figure 3)[63, 90, 223, 242–244, 256–258]. Bassoon and CAST/ELKS2/Erc2 interact with the P/Q-type VGCC β subunits [90, 258], Bassoon interacts indirectly with P/Q-type VGCCs [223], and RIM1/2 interacts with P/Q- and N-type VGCC α subunits and β subunit [242–244, 256].…”

“…In addition, a number of active zone proteins interact with different subunits of the VGCCs (Figure 3)[63, 90, 223, 242–244, 256–258]. Bassoon and CAST/ELKS2/Erc2 interact with the P/Q-type VGCC β subunits [90, 258], Bassoon interacts indirectly with P/Q-type VGCCs [223], and RIM1/2 interacts with P/Q- and N-type VGCC α subunits and β subunit [242–244, 256]. Bassoon and RIM1 have also been shown to inhibit the inactivation properties of P/Q-type VGCCs, prolonging the opening of these calcium channels localized with Bassoon and RIM1 compared to VGCCs without interacting with these active zone proteins [189, 242, 243].…”