Similar molecular determinants on Rem mediate two distinct modes of inhibition of CaV1.2 channels.
Channels (Austin)
; 10(5): 379-394, 2016 Sep 02.
Article
em En
| MEDLINE
| ID: mdl-27115600
ABSTRACT
Rad/Rem/Rem2/Gem (RGK) proteins are Ras-like GTPases that potently inhibit all high-voltage-gated calcium (CaV1/CaV2) channels and are, thus, well-positioned to tune diverse physiological processes. Understanding how RGK proteins inhibit CaV channels is important for perspectives on their (patho)physiological roles and could advance their development and use as genetically-encoded CaV channel blockers. We previously reported that Rem can block surface CaV1.2 channels in 2 independent ways that engage distinct components of the channel complex (1) by binding auxiliary ß subunits (ß-binding-dependent inhibition, or BBD); and (2) by binding the pore-forming α1C subunit N-terminus (α1C-binding-dependent inhibition, or ABD). By contrast, Gem uses only the BBD mechanism to block CaV1.2. Rem molecular determinants required for BBD CaV1.2 inhibition are the distal C-terminus and the guanine nucleotide binding G-domain which interact with the plasma membrane and CaVß, respectively. However, Rem determinants for ABD CaV1.2 inhibition are unknown. Here, combining fluorescence resonance energy transfer, electrophysiology, systematic truncations, and Rem/Gem chimeras we found that the same Rem distal C-terminus and G-domain also mediate ABD CaV1.2 inhibition, but with different interaction partners. Rem distal C-terminus interacts with α1C N-terminus to anchor the G-domain which likely interacts with an as-yet-unidentified site. In contrast to some previous studies, neither the C-terminus of Rem nor Gem was sufficient to inhibit CaV1/CaV2 channels. The results reveal that similar molecular determinants on Rem are repurposed to initiate 2 independent mechanisms of CaV1.2 inhibition.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Monoméricas de Ligação ao GTP
/
Canais de Cálcio Tipo L
Limite:
Animals
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Humans
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Male
Idioma:
En
Revista:
Channels (Austin)
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Estados Unidos