Transcription of the T-cell potassium channel Kv1.3 is regulated by a GC-rich TATA-less promoter

The basal promoter of Kv1.3, the voltage-gated K+ channel in T cells, lies within a GC-rich SmaI/SacI fragment lacking a TATA box and contains two SP1 sites together with two repeats of the motif GGGCGG. The promoters of many housekeeping genes as well as three related potassium channel genes (Kv1.4, Kv1.5, and Kv3.1) are also TATA-less and GC-rich, suggesting that all these genes may use common transcriptional regulation mechanisms. Upstream positive regulatory (enhancer) elements lie in a region containing two overlapping TFIID sites and two SP1 motifs. Primer extension shows that the 5-NCR of Kv1.3 is significantly shorter (length 150 bp) than the corresponding regions (> 1,000 bp) of other closely related genes (Kv1.1, Kv1.2, Kv1.4). The 5'-NCR and the entire coding region of Kv1.3 are contained in a single uninterrupted exon spanning similar to 1.65 kb. The diversity of Kv1.3 mRNAs (3.5-9.5 kb) found in lymphocytes and brain may, therefore, result from either alternate splicing in the 3-UTR or alternate use of polyadenylation sites.