Human Calcium-Activated Potassium Channel GeneKCNN4Maps to Chromosome 19q13.2 in the Region Deleted in Diamond–Blackfan Anemia

Delineation of the Clotrimazole/TRAM-34 Binding Site on the Intermediate Conductance Calcium-activated Potassium Channel, IKCa1

“…TRAM-30 was prepared by refluxing clotrimazole (2.00 g, 5.81 mmol) with an excess of methyl iodide in butanone for 36 h. The reaction mixture was evaporated to dryness. On addition of petroleum ether to the resulting oily residue and intensive cooling and scratching, the material began to solidify and was then washed thoroughly with acetone and petroleum ether (mp: 139°C; 1H Clones and Mutants-The cloning of human IKCa1 (GenBank TM accession number AF033021) and human SKCa3 containing 19 polyglutamines in the N terminus (GenBank TM accession numbers AF031815 and AJ251016) have been reported previously (2,18,19). Both channel genes were subcloned into the pEGFP-C1 vector (CLON-TECH) in frame with GFP.…”

Calmodulin Mediates Calcium-dependent Activation of the Intermediate Conductance KCa Channel,IKCa1

“…Clones, Mutants, and Vectors-We have previously reported the cloning of hIKCa1 (22,23), hSKCa3 (15), and mKv1.3 (31). Drosophila wild-type (WT) and mutant (B1234Q) CAMs with differing Ca 2ϩ sensitivities have been reported previously (32,33).…”

“…IK Ca channels, unlike SK Ca channels, are predominantly expressed in peripheral tissues, including those of the hematopoietic system, colon, lung, placenta, and pancreas (17)(18)(19)(20)(21)(22)(23). These channels have intermediate single channel conductance values of 11-40 pS and can be pharmacologically distinguished from SK Ca channels by their sensitivity to block by ChTX and clotrimazole and by their insensitivity to apamin (20,22).…”

“…At least one gene encoding an IK Ca channel has been cloned from human and mouse tissues. Called IKCa1 (also called KCa4, SK4, and KCNN4), this gene has been shown to encode the native IK Ca channel in human T-lymphocytes (22,23) and erythrocytes (24 -27); some patients with Diamond-Blackfan anemia lack one allele of this gene (23). hIKCa1 shares little sequence identity with the Slo proteins, and only about 40% identity with the SKCa1-3 gene products.…”

Mechanisms underlying the cardiac pacemaker: the role of SK4 calcium-activated potassium channels

“…The SK4 intermediate calcium-activated channel (K Ca 3.1) is encoded by the gene KCNN4, which is localized in the q13.2 region of human chromosome 19 [152] . Historically, this channel was discovered by Gardos in 1958, when he noted a correlation between the potassium outflow from erythrocytes and the intracellular EDTA/calcium competition [153] .…”