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Modulation of cardiac Ca 2+ channels in Xenopus oocytes by protein kinase C
Author(s) -
Singer-Lahat Dafna,
Gershon Eli,
Lotan Ilana,
Hullin Roger,
Biel Martin,
Flockerzi Veit,
Hofmann Franz,
Dascal Nathan
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80980-u
Subject(s) - xenopus , protein kinase c , protein subunit , staurosporine , protein kinase a , phorbol , microbiology and biotechnology , rna , chemistry , biology , endocrinology , kinase , biochemistry , gene
L‐Type calcium channel was expressed in Xenopus laevis oocytes injected with RNAs coding for different cardiac Cu 2+ channel subunits, or with total heart RNA. The effects of activation of protein kinase C (PKC) by the phorbol ester PMA (4β‐phorbol 12‐myristate 13‐acetate) were studied. Currents through channels composed of the main (α 1 ) subunit alone were initially increased and then decreased by PMA. A similar biphasic modulation was observed when the α 1 subunit was expressed in combination with α 2 /δ, β and/or γ subunits, and when the channels were expressed following injection of total rat heart RNA. No effects on the voltage dependence of activation were observed. The effects of PMA were blocked by staurosporine, a protein kinase inhibitor. β subunit moderated the enhancement caused by PMA. We conclude that both enhancement and inhibition of cardiac L‐type Ca 2+ currents by PKC are mediated via an effect on the α 1 subunit, while the β subunit may play a mild modulatory role.