TY - JOUR
T1 - Interactions between N and C termini of α1C subunit regulate inactivation of CaV1.2 L-type Ca2+ channel
AU - Guggenheimer, Adva Benmocha
AU - Almagor, Lior
AU - Tsemakhovich, Vladimir
AU - Tripathy, Debi Ranjan
AU - Hirsch, Joel A.
AU - Dascal, Nathan
N1 - Publisher Copyright:
© 2016 Taylor & Francis Group, LLC.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - The modulation and regulation of voltage-gated Ca2+ channels is affected by the pore-forming segments, the cytosolic parts of the channel, and interacting intracellular proteins. In this study we demonstrate a direct physical interaction between the N terminus (NT) and C terminus (CT) of the main subunit of the L-type Ca2+ channel CaV1.2, α1C, and explore the importance of this interaction for the regulation of the channel. We used biochemistry to measure the strength of the interaction and to map the location of the interaction sites, and electrophysiology to investigate the functional impact of the interaction. We show that the full-length NT (amino acids 1-154) and the proximal (close to the plasma membrane) part of the CT, pCT (amino acids 1508-1669) interact with sub-micromolar to low-micromolar affinity. Calmodulin (CaM) is not essential for the binding. The results further suggest that the NT-CT interaction regulates the channel’s inactivation, and that Ca2+, presumably through binding to calmodulin (CaM), reduces the strength of NT-CT interaction. We propose a molecular mechanism in which NT and CT of the channel serve as levers whose movements regulate inactivation by promoting changes in the transmembrane core of the channel via S1 (NT) or S6 (pCT) segments of domains I and IV, accordingly, and not as a kind of pore blocker. We hypothesize that Ca2+- CaM-induced changes in NT-CT interaction may, in part, underlie the acceleration of CaV1.2 inactivation induced by Ca2+ entry into the cell.
AB - The modulation and regulation of voltage-gated Ca2+ channels is affected by the pore-forming segments, the cytosolic parts of the channel, and interacting intracellular proteins. In this study we demonstrate a direct physical interaction between the N terminus (NT) and C terminus (CT) of the main subunit of the L-type Ca2+ channel CaV1.2, α1C, and explore the importance of this interaction for the regulation of the channel. We used biochemistry to measure the strength of the interaction and to map the location of the interaction sites, and electrophysiology to investigate the functional impact of the interaction. We show that the full-length NT (amino acids 1-154) and the proximal (close to the plasma membrane) part of the CT, pCT (amino acids 1508-1669) interact with sub-micromolar to low-micromolar affinity. Calmodulin (CaM) is not essential for the binding. The results further suggest that the NT-CT interaction regulates the channel’s inactivation, and that Ca2+, presumably through binding to calmodulin (CaM), reduces the strength of NT-CT interaction. We propose a molecular mechanism in which NT and CT of the channel serve as levers whose movements regulate inactivation by promoting changes in the transmembrane core of the channel via S1 (NT) or S6 (pCT) segments of domains I and IV, accordingly, and not as a kind of pore blocker. We hypothesize that Ca2+- CaM-induced changes in NT-CT interaction may, in part, underlie the acceleration of CaV1.2 inactivation induced by Ca2+ entry into the cell.
KW - Binding
KW - C-terminus
KW - Ca1.2
KW - Calcium channel
KW - Calmodulin
KW - Inactivation
KW - L-type
KW - N-terminus
UR - http://www.scopus.com/inward/record.url?scp=84964016593&partnerID=8YFLogxK
U2 - 10.1080/19336950.2015.1108499
DO - 10.1080/19336950.2015.1108499
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C2 - 26577286
AN - SCOPUS:84964016593
SN - 1933-6950
VL - 10
SP - 55
EP - 68
JO - Channels
JF - Channels
IS - 1
ER -