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Putative small conductance Ca2+‐sensitive K+ channels isoforms and splice variants in mitochondria of guinea pig cardiac ventricular myocytes
Author(s) -
Yang Meiying,
Camara Amadou K.S.,
Bienengraeber Martin,
Kwok WaiMeng,
Stowe David F.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1209.12
Subject(s) - gene isoform , myocyte , splice , complementary dna , alternative splicing , microbiology and biotechnology , mitochondrion , biology , gene , chemistry , biochemistry
Small Ca 2+ ‐sensitive K + channels (SK Ca ) exist in many cell types including cardiac atrial and ventricular. There are 3 isoforms of SK Ca , i.e. SK Ca 1, 2, and 3. Activation of SK Ca channels may protect against ischemia (I) and reperfusion (R) injury. Recently we found SK Ca channels exist in the inner mitochondrial membrane (IMM) of guinea pig cardiac ventricular myocytes and that SK Ca channel opening protects against cardiac IR injury. It is unknown which SK Ca isoforms and splice variants are specific for cardiac cell IMM so we searched for the gene products that might confer their distinct structural and functional characteristics. SK Ca is expressed in cardiac ventricular cells, so ventricular tissue devoid of endovascular cells were used to extract total RNA, which was then reverse transcribed to cDNA. The resulting cDNA was amplified with SK Ca 1, 2 and 3 gene‐specific primers. Results showed that both SK Ca 2 and 3 were amplified, which suggests both isoforms may be expressed in ventricular mitochondria. Gene and amino acid sequence alignments showed the amplified SK Ca 3 to be SK Ca 3.1, which lacks residues 478–499, present in SK Ca 3.2. Similar to rat SK Ca 3.1, guinea pig SK Ca 3.1 displayed a conserved COOH‐terminal but did not have a poly‐Glu repeat region. Our results indicate that in ventricular cell IMM there may exist two SK Ca isoforms and at least one SK Ca 3 splice variant that can be functionally characterized. (NIH, VA)