Molecular Determinants of Modulation of CaV2.1 Channels by Visinin-like Protein 2

Evanthia Nanou,Gilbert Q Martinez,Todd Scheuer,William A Catterall

doi:10.1074/jbc.m111.292581

Evanthia Nanou, Gilbert Q Martinez + Show 2 more

Open Access

https://doi.org/10.1074/jbc.m111.292581

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Abstract

CaV2.1 channels, which conduct P/Q-type Ca2+ currents, initiate synaptic transmission at most synapses in the central nervous system. Ca2+/calmodulin-dependent facilitation and inactivation of these channels contributes to short-term facilitation and depression of synaptic transmission, respectively. Other calcium sensor proteins displace calmodulin (CaM) from its binding site, differentially regulate CaV2.1 channels, and contribute to the diversity of short-term synaptic plasticity. The neuronal calcium sensor protein visinin-like protein 2 (VILIP-2) inhibits inactivation and enhances facilitation of CaV2.1 channels. Here we examine the molecular determinants for differential regulation of CaV2.1 channels by VILIP-2 and CaM by construction and functional analysis of chimeras in which the functional domains of VILIP-2 are substituted in CaM. Our results show that the N-terminal domain, including its myristoylation site, the central α-helix, and the C-terminal lobe containing EF-hands 3 and 4 of VILIP-2 are sufficient to transfer its regulatory properties to CaM. This regulation by VILIP-2 requires binding to the IQ-like domain of CaV2.1 channels. Our results identify the essential molecular determinants of differential regulation of CaV2.1 channels by VILIP-2 and define the molecular code that these proteins use to control short-term synaptic plasticity.

Highlights

Regulation of calcium channels by calcium sensor proteins mediates short-term synaptic plasticity
These results indicate that the IQ-like motif (IM)-AA mutation is not sufficient to prevent the effect of visinin-like protein 2 (VILIP-2) to inhibit Ca2ϩ-dependent inactivation. Both VILIP-2 and N12H34 failed to induce facilitation of the CaV2.1/IM-AA channels (Fig. 5, C and F). These results demonstrate that binding of VILIP-2 to the IQ-like domain of CaV2.1 channels is a primary requirement for Ca2ϩ-dependent facilitation but not for Ca2ϩ-dependent inactivation
N-terminal Lobes of Calcium-binding protein 1 (CaBP1) and VILIP-2 Enhance Ca2ϩ-dependent Inactivation—CaM and neuronal CaS proteins contain four EF-hand motifs separated into two lobes by a central ␣-helical domain

Summary

Background

Regulation of calcium channels by calcium sensor proteins mediates short-term synaptic plasticity. Other calcium sensor proteins displace calmodulin (CaM) from its binding site, differentially regulate CaV2.1 channels, and contribute to the diversity of short-term synaptic plasticity. Our results show that the N-terminal domain, including its myristoylation site, the central ␣-helix, and the C-terminal lobe containing EF-hands 3 and 4 of VILIP-2 are sufficient to transfer its regulatory properties to CaM This regulation by VILIP-2 requires binding to the IQ-like domain of CaV2.1 channels. Our results show that the N-terminal domain up to the first EF-hand plus the C-terminal lobe of VILIP-2, together with its interlobe ␣-helix, are both necessary and sufficient to confer VILIP-2-like regulatory properties on CaM These results further define the molecular code that is used for CaS protein-dependent modulation of short-term synaptic plasticity

EXPERIMENTAL PROCEDURES

RESULTS

F N12H34

DISCUSSION