Abstract
Two novel K+ channel alpha subunits, named Kv9.1 and Kv9.2, have been cloned. The Kv9.2 gene is situated in the 8q22 region of the chromosome. mRNAs for these two subunits are highly and selectively expressed in the nervous system. High levels of expressions are found in the olfactory bulb, cerebral cortex, hippocampal formation, habenula, basolateral amygdaloid nuclei, and cerebellum. Interestingly Kv9.1 and Kv9.2 colocalized with Kv2.1 and/or Kv2.2 alpha subunits in several regions of the brain. Neither Kv9.1 nor Kv9.2 have K+ channel activity by themselves, but both modulate the activity of Kv2.1 and Kv2.2 channels by changing kinetics and levels of expression and by shifting the half-inactivation potential to more polarized values. This report also analyzes the changes in electrophysiological properties of Kv2 subunits induced by Kv5.1 and Kv6.1, two other modulatory subunits. Each modulatory subunit has its own specific properties of regulation of the functional Kv2 subunits, and they can lead to extensive inhibitions, to large changes in kinetics, and/or to large shifts in the voltage dependencies of the inactivation process. The increasing number of modulatory subunits for Kv2.1 and Kv2.2 provides an amazingly new capacity of functional diversity.
Highlights
Voltage-gated potassium channels (Kv)1 form the largest and most diversified class of ion channels
We have previously shown that a high level of expression of some cloned Kϩ channels could lead to high magnitude Kϩ currents with major kinetic and voltage-dependence modifications when compared with currents of lower intensity [32, 40]
Cloning of Two New Putative Voltage-gated Kϩ Channels Which Define the New Kv9 Subfamily Related to the Modulatory ␣ Subunits—The Kv8.1 subunit is a new Kϩ channel subunit which is inactive by itself and which has recently been described to regulate both active subunits of the Kv2 potassium channel subfamily [21, 22]
Summary
Cloning of Kv9.1 and Kv9.2—A BLAST search of the expressed sequence tag (EST) data base, using the query peptide sequence of Kv8.1, reveals two groups of matching EST coding for two new homologues of Kv channels. To link the T7 tag epitope (MASMTGGQQMG) to the N terminus of Kv9.2, the double-stranded oligonucleotide 5Ј-GGGCTAGCTGATCAGAGGCCTCACCATGGCTAGTATGACTGGAGGACAGCAAATGGGATATCGCGACCAGCTGACTCGAGAATTCG-3Ј, which contains the restriction sites NheI and EcoRI in its extremities, was subcloned into the pCI vector (Promega) at the corresponding sites. This construction designated T7.tag-pCI contains EcoRV, NruI, PvuII, and XhoI cloning sites. The cells were incubated for 2 h with a mixture of anti-FLAG M2 monoclonal antibody (1/150 dilution, Kodak) or T7.Tag monoclonal antibody (1/250, NOVAGEN) with a BS solution (2% bovine serum albumin in PBS), followed by washing with PBS and incubation for 1 h with fluorescein isothiocyanate-conjugated goat antimouse Ig (1/200, Sigma) in BS. The members of subfamilies used and their accession numbers are as follows: mKv1.1, Y00305; hKv1.3, M85217; rKv2.1, X16476; rKv2.2, M77482; rKv3.3, M84211; rKv3.4, X62841; rKv4.1, S64320; rKv5.1, M81783; rKv6.1, M81784; aKv7.1, L35766; and Kv8.1, U62810
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
