title: Linker flexibility of IVS3-S4 loops modulates voltage-dependent activation of L-type Ca2+channels.
abstract: Extracellular S3-S4 linkers of domain IV (IVS3-S4) of L-type Ca2+channels (CaV1) are subject to alternative splicing, resulting into distinct gating profiles serving for diverse physiological roles. However, it has remained elusive what would be the determining factor of IVS3-S4 effects on CaV1 channels. In this study, we systematically compared IVS3-S4 variants from CaV1.1-1.4, and discover that the flexibility of the linker plays a prominent role in gating characteristics. Chimeric analysis and mutagenesis demonstrated that changes in half activation voltage (V1/2) or activation time constant (τ) are positively correlated with the numbers of flexible glycine residues within the linker. Moreover, antibodies that reduce IVS3-S4 flexibility negatively shifted V1/2, emerging as a new category of CaV1 enhancers. In summary, our results suggest that the flexibility or rigidity of IVS3-S4 linker underlies its modulations on CaV1 activation (V1/2and τ), paving the way to dissect the core mechanisms and to develop innovative perturbations pertaining to voltage-sensing S4 and its vicinities.
authors.affiliation: a Department of Biomedical Engineering , School of Medicine, Tsinghua University , Beijing , China.
authors.forename: Nan
authors.initials: N
authors.lastname: Liu
authors.affiliation: a Department of Biomedical Engineering , School of Medicine, Tsinghua University , Beijing , China.
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Liu
authors.affiliation: a Department of Biomedical Engineering , School of Medicine, Tsinghua University , Beijing , China.
authors.forename: Yaxiong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: a Department of Biomedical Engineering , School of Medicine, Tsinghua University , Beijing , China.|b School of Life Sciences, Tsinghua University , Beijing , China.|c IDG/McGovern Institute for Brain Research, Tsinghua University , Beijing , China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Liu
mesh_terms: D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*
chemical_list: D020746:Calcium Channels, L-Type
keywords: L-type Ca2+ channels; S3-S4 loop; linker flexibility; voltage sensing domain; voltage-dependent activation