None of the polypeptides share 100% sequence identity.
Co-injection experiments in Xenopus oocytes were
used to test for formation of functional heterodimers between Sh
subfamily members. In fact, no functional heterodimers (as shown by novel
current kinetics) were detected when all pairwise combinations of the four
tested. The independence of each channel system was retained even when all
four were co-expressed.
Shal protein was expressed in Xenopus oocytes and characterized with respect to kinetics (rate of macroscopic current activation and inactivation) and voltage sensitivity of steady-state inactivation. Those properties were compared among the Sh subfamily members and found to vary widely. Shal encodes the transient (A current)subtype of potassium channel and appears to function as a homomultimer.
The N-terminus may be important in determining the rate of inactivation of the channel while the tail may play a role in modulation of channel activity and/or targeting of the channel to specific subcellular compartments.
Heterotetramer of potassium channel proteins (By similarity). Interacts (via C-terminal dendritic targeting motif) with SIDL.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Shal using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Shal in GBrowse 2
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
The monkey Cos cell line is a reasonable system for transient expression of K+ channels, particularly those with fast inactivation kinetics.
Shal encodes virtually all the transient K+ currents observed in embryonic neurons.
Yeast two-hybrid system studies demonstrate the association of the hydrophilic N-terminal domains of the genes encoding channel proteins plays an important role in determining the specificity of α subunit association to form heteromultimeric potassium channels.
Although Sh, Shal, Shab and Shaw proteins share a conserved structral organisation, their potassium channel currents (expressed in Xenopus oocytes) differ greatly in individual kinetic properties and voltage sensitivity.
Sh, Shal, Shab and Shaw encode voltage gated potassium channels with widely varying kinetics (rate of macroscopic current activation and inactivation) and voltage sensitivity of steady state inactivation.
Potassium channel diversity could result from an extended gene family as well as from alternate splicing of the Sh primary transcript.
Expression of Shal cDNA-derived mRNA in Xenopus oocytes (Wei, Covarrubias, Butler, Baker, Pak and Salkoff, 1990a; Wei, Covarrubias, Butler, Baker, Pak and Salkoff, 1990b) leads to potassium currents intermediate in kinetic properties between those associated with Sh (using the heterologous egg system) and Shaw (same kind of experiment), i.e., between very rapid activation/inactivation (Sh-encoded 'A'-type channels) and quite slow kinetics (Shaw-encoded, delayed-rectifier-type channels).