A sequence in the carboxy-terminus of the alpha(1C) subunit important for targeting, conductance and open probability of L-type Ca(2+) channels.
The role of the 80-amino acid motif 1572-1651 in the C-terminal tail of alpha(1C) Ca(2+) channel subunits was studied by comparing properties of the conventional alpha(1C,77) channel expressed in HEK-tsA201 cells to three isoforms carrying alterations in this motif. Replacement of amino acids 1572-1651 in alpha(1C,77) with 81 non-identical residues leading to alpha(1C,86) impaired membrane targeting and cluster formation of the channel. Similar to alpha(1C, 86), substitution of its 1572-1598 (alpha(1C,77L)) or 1595-1652 (alpha(1C,77K)) segments into the alpha(1C,77) channel yielded single-channel Ba(2+) currents with increased inactivation, reduced open probability and unitary conductance, when compared to the alpha(1C,77) channel. Thus, the C-terminal sequence 1572-1651 of the alpha(1C) subunit is important for membrane targeting, permeation and open probability of L-type Ca(2+) channels.
Kepplinger
K J
KJ
Institute for Biophysics, University of Linz, Altenbergerstr, 69, A-4040 Linz, Austria.
Kahr
H
H
Förstner
G
G
Sonnleitner
M
M
Schindler
H
H
Schmidt
T
T
Groschner
K
K
Soldatov
N M
NM
Romanin
C
C
D000595:Amino Acid Sequence; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000502:physiology*; D002460:Cell Line; D006801:Humans; D015640:Ion Channel Gating; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D011336:Probability; D020033:Protein Isoforms / Q000737:chemistry / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D020746:Calcium Channels, L-Type; D020033:Protein Isoforms; D011994:Recombinant Proteins