TY - JOUR
T1 - min K channels form by assembly of at least 14 subunits
AU - Tzounopoulos, T.
AU - Guy, H. R.
AU - Durell, S.
AU - Adelman, J. P.
AU - Maylie, J.
PY - 1995/10/10
Y1 - 1995/10/10
N2 - Injection of rain K mRNA into Xenopus oocytes results in expression of slowly activating voltage-dependent potassium channels, distinct from those induced by expression of other cloned potassium channels. The min K protein also differs in structure, containing only a single predicted transmembrane domain. While it has been demonstrated that all other cloned potassium channels form by association of four independent subunits, the number of min K monomers which constitute a functional channel is unknown. In rat min K, replacement of Ser-69 by Ala (S69A) causes a shift in the current-voltage (I- V) relationship to more depolarized potentials; currents are not observed at potentials negative to 0 reV. To determine the subunit stoichiometry of min K channels, wild-type and S69A subunits were coexpressed. Injections of a constant amount of wild-type mRNA with increasing amounts of S69A mRNA led to potassium currents of decreasing amplitude upon voltage commands to -20 mV. Applying a binomial distribution to the reduction of current amplitudes as a function of the different coinjection mixtures yielded a subunit stoichiometry of at least 14 monomers for each functional rain K channel. A model is presented for how rain K subunits may form a channel.
AB - Injection of rain K mRNA into Xenopus oocytes results in expression of slowly activating voltage-dependent potassium channels, distinct from those induced by expression of other cloned potassium channels. The min K protein also differs in structure, containing only a single predicted transmembrane domain. While it has been demonstrated that all other cloned potassium channels form by association of four independent subunits, the number of min K monomers which constitute a functional channel is unknown. In rat min K, replacement of Ser-69 by Ala (S69A) causes a shift in the current-voltage (I- V) relationship to more depolarized potentials; currents are not observed at potentials negative to 0 reV. To determine the subunit stoichiometry of min K channels, wild-type and S69A subunits were coexpressed. Injections of a constant amount of wild-type mRNA with increasing amounts of S69A mRNA led to potassium currents of decreasing amplitude upon voltage commands to -20 mV. Applying a binomial distribution to the reduction of current amplitudes as a function of the different coinjection mixtures yielded a subunit stoichiometry of at least 14 monomers for each functional rain K channel. A model is presented for how rain K subunits may form a channel.
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U2 - 10.1073/pnas.92.21.9593
DO - 10.1073/pnas.92.21.9593
M3 - Article
C2 - 7568179
AN - SCOPUS:0028883835
SN - 0027-8424
VL - 92
SP - 9593
EP - 9597
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 21
ER -