TY - JOUR
T1 - Molecular determinants of L-type Ca2+ channel inactivation
T2 - Segment exchange analysis of the carboxyl-terminal cytoplasmic motif encoded by exons 40-42 of the human α(1C) subunit gene
AU - Soldatov, Nikolai M.
AU - Oz, Murat
AU - O'Brien, Kathleen A.
AU - Abernethy, Darrell R.
AU - Morad, Martin
PY - 1998/1/9
Y1 - 1998/1/9
N2 - Recently we have described a splice variant of the L-type Ca2+ channel (α(1C,86)) in which 80 amino acids (1572-1651) of the conventional α(1C,77) were substituted by another 81 amino acids due to alternative splicing of exons 40-42. Ba2+ current (I(Ba)) through α(1C,86) exhibited faster inactivation kinetics, was strongly voltage-dependent, and had no Ca2+ - dependent inactivation. An oligonucleotide-directed segment substitution and expression of the mutated channels in Xenopus oocytes were used to study the molecular determinants for gating of the channel within the 80-amino acid domain. Replacement of segments 1572-1598 or 1595-1652 of the 'slow' α(1C,77) channel with the respective segments of the 'fast' α(1C,86) gave rise to rapidly inactivating α(1C,86) like channel isoforms. We found that replacement of either motifs 1572IKTEG1576 or 1600LLDQV1604 of α(1C,77) with the respective sequences of α(1C,86) caused strong but partial acceleration of I(Ba) inactivation. Replacement of both sequences produced an α(1C,86)-like fast channel which had no Ca2+ -dependent inactivation. These results support the hypothesis that motifs 1572-1576 and 1600-1604 of α(1C,77) contribute cooperatively to inactivation kinetics of α(1C) and are critical for Ca2+ -dependent inactivation of the channel.
AB - Recently we have described a splice variant of the L-type Ca2+ channel (α(1C,86)) in which 80 amino acids (1572-1651) of the conventional α(1C,77) were substituted by another 81 amino acids due to alternative splicing of exons 40-42. Ba2+ current (I(Ba)) through α(1C,86) exhibited faster inactivation kinetics, was strongly voltage-dependent, and had no Ca2+ - dependent inactivation. An oligonucleotide-directed segment substitution and expression of the mutated channels in Xenopus oocytes were used to study the molecular determinants for gating of the channel within the 80-amino acid domain. Replacement of segments 1572-1598 or 1595-1652 of the 'slow' α(1C,77) channel with the respective segments of the 'fast' α(1C,86) gave rise to rapidly inactivating α(1C,86) like channel isoforms. We found that replacement of either motifs 1572IKTEG1576 or 1600LLDQV1604 of α(1C,77) with the respective sequences of α(1C,86) caused strong but partial acceleration of I(Ba) inactivation. Replacement of both sequences produced an α(1C,86)-like fast channel which had no Ca2+ -dependent inactivation. These results support the hypothesis that motifs 1572-1576 and 1600-1604 of α(1C,77) contribute cooperatively to inactivation kinetics of α(1C) and are critical for Ca2+ -dependent inactivation of the channel.
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U2 - 10.1074/jbc.273.2.957
DO - 10.1074/jbc.273.2.957
M3 - Article
C2 - 9422756
AN - SCOPUS:0031964546
SN - 0021-9258
VL - 273
SP - 957
EP - 963
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 2
ER -