Recombinant Rat Potassium channel subfamily K member 15 (Kcnk15)
Description
Genetic and Protein Identification
Rat Kcnk15 is encoded by the gene with ID 156873, which produces a protein documented under multiple database identifiers including mRNA reference sequence NM_130813.1, protein reference sequence NP_570826.1, and UniProt ID Q8R5I0 . The gene is also known by several alternate nomenclatures including TASK-5 (TWIK-related acid-sensitive K+ channel 5), reflecting its classification within the acid-sensitive subfamily of two-pore domain potassium channels . This classification system helps researchers understand potential functional similarities with other members of this channel subfamily.
Biophysical Properties
Kcnk15 (TASK-5) belongs to the acid-sensitive subgroup of K2P channels, suggesting sensitivity to extracellular pH changes . Despite this classification, direct functional evidence of channel activity has been difficult to establish in heterologous expression systems. Unlike other members of the TASK family that show clear pH-dependent regulation, Kcnk15 has not demonstrated measurable channel activity when expressed alone, suggesting it may require association with auxiliary proteins or specific cellular environments to form functional channels . This characteristic distinguishes it from better-characterized members of the K2P family and presents unique challenges for electrophysiological characterization.
Neurophysiological Significance
Studies have identified selective and high expression of TASK-5 in auditory brainstem neurons, suggesting a specialized role in auditory processing . This localized expression pattern indicates that Kcnk15 may contribute to the specific electrophysiological properties required for auditory signal processing. Research examining changes in expression following bilateral cochlear ablation provides evidence that TASK-5 expression is regulated by auditory activity, potentially participating in neuroplastic responses to sensory deprivation . This finding places Kcnk15 within the broader context of activity-dependent regulation of ion channels in sensory systems.
Comparative Analysis with Related K2P Channels
As shown in the comprehensive classification of two-pore domain potassium channels, Kcnk15 (TASK-5) is categorized among acid-sensitive channels, alongside TASK-1 (Kcnk3) and TASK-3 (Kcnk9) . While these related channels have well-established functions in setting resting membrane potential and responding to changes in extracellular pH, Kcnk15's functional properties remain less clearly defined. The table below summarizes the classification and reported functions of various K2P channel members, providing context for understanding Kcnk15's potential role:
| Gene name | Common name | Classification | Reported function |
|---|---|---|---|
| Kcnk15 | TASK5 | Acid sensitive channel | TWIK-related acid-sensitive potassium channel; Sensitive to changes in pH |
| Kcnk3 | TASK1 | Acid sensitive channel | Inhibition by acidic external pH; voltage and [K+] dependant |
| Kcnk9 | TASK3 | Acid sensitive channel | Inhibited reversibly by acidic extracellular pH |
| Kcnk1 | TWIK1 | Weak inward rectifier | Activated by desumoylation; upregulated by PKC activation; downregulated by intracellular acidosis |
| Kcnk6 | TWIK2 | Weak inward rectifier | Inhibited by intracellular but not extracellular acidosis |
| Kcnk2 | TREK1 | Unsaturated fatty acid and stretch-activated | Activated by increasing mechanical pressure applied to cell membrane |
| Kcnk10 | TREK2 | Unsaturated fatty acid and stretch-activated | Activity elicited by fatty acid-stimulation and increased mechanical pressure applied to cell membrane |
| Kcnk4 | TRAAK | Unsaturated fatty acid and stretch-activated | Activity elicited by increasing mechanical pressure applied to cell membrane |
| Kcnk13 | THIK1 | Halothane sensitive channels | Tandem pore domain halothane inhibited K(+) channel |
| Kcnk12 | THIK2 | Halothane sensitive channels | Tandem pore domain halothane inhibited K(+) channel |
This comparative analysis highlights the diversity of K2P channels and contextualizes Kcnk15's position within this important ion channel family .
Expression Systems and Methods
Recombinant rat Kcnk15 protein has been successfully expressed in mammalian cell systems, particularly HEK293 cells . This expression system provides an environment capable of performing post-translational modifications necessary for proper protein folding and potentially functional analysis. The use of mammalian expression systems rather than bacterial or insect cell systems reflects the complexity of membrane protein expression and the importance of appropriate glycosylation and processing for channel proteins.
Antibodies and Detection Methods
Multiple antibodies have been developed for detecting Kcnk15 in various experimental contexts. These include:
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Anti-KCNK15 C-Terminal antibodies (such as SAB4502647) produced in rabbit, suitable for ELISA, immunohistochemistry, and western blot applications
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Anti-KCNK15 Prestige Antibodies (such as HPA064861) for immunohistochemical applications
These immunological tools enable the visualization and quantification of Kcnk15 expression in tissue samples and cell cultures, facilitating studies of channel distribution and regulation under various physiological and pathological conditions.
Gene Knockdown and Silencing Technologies
For functional studies investigating the physiological role of Kcnk15, several gene manipulation technologies are available:
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siRNA (small interfering RNA) designed using proprietary algorithms for specific targeting of Kcnk15 mRNA
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shRNA (short hairpin RNA) for stable knockdown of Kcnk15 expression in long-term experiments
These molecular tools allow researchers to specifically reduce Kcnk15 expression, providing insights into the channel's contribution to cellular physiology through loss-of-function approaches.
Quantitative Expression Analysis
Real-time quantitative PCR has been employed to examine changes in Kcnk15 expression under various experimental conditions, including following bilateral cochlear ablation in rats . This technique allows precise measurement of changes in mRNA levels, providing insight into transcriptional regulation of the channel in response to physiological perturbations. Such studies contribute to understanding the role of Kcnk15 in neuroplasticity and adaptive responses to sensory deprivation.
Predicted Functional Partners
String database analysis identifies several predicted functional partners for rat Kcnk15, suggesting potential protein-protein interactions that may influence channel function or regulation:
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Kcnk18 (Potassium channel subfamily K member 18) - Produces rapidly activating outward rectifier K+ currents and may function as a background potassium channel setting resting membrane potential, with an interaction score of 0.689
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Kcnk7 (Potassium channel subfamily K member 7) - Another K2P family member with an interaction score of 0.683
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Kcnk4 (Potassium channel subfamily K member 4) - A voltage-insensitive potassium channel activated by mechanical forces and pH changes, with an interaction score of 0.681
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Kcnk12 (Potassium channel subfamily K member 12) - A probable potassium channel subunit that may need to associate with other proteins to form functional channels, with an interaction score of 0.674
These predicted interactions provide potential research directions for understanding the functional complexes that may include Kcnk15 and contribute to its physiological roles.
Heterodimerization Potential
The lack of observed channel activity when Kcnk15 is expressed alone suggests it may form heterodimers with other K2P family members to create functional channels . This hypothesis is supported by the structural characteristics of K2P channels, which typically function as dimers, and the existence of known heterodimeric combinations within the family. Investigation of potential heterodimeric partners represents an important direction for future research into Kcnk15 function.
Functional Characterization Challenges
A primary challenge in Kcnk15 research remains establishing conditions under which the channel demonstrates measurable activity in controlled experimental systems. This may require:
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Identification of potential heterodimeric partners
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Discovery of specific auxiliary proteins or cellular factors required for channel function
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Determination of unique stimuli or conditions that activate the channel
Resolving these questions would significantly advance understanding of Kcnk15's physiological role and potential therapeutic relevance.
Neurophysiological Investigations
Given the selective expression of Kcnk15 in auditory brain stem neurons, further investigation into its role in auditory processing represents a promising research direction . Key questions include:
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How does Kcnk15 contribute to the specific electrophysiological properties of auditory neurons?
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What role does Kcnk15 play in activity-dependent plasticity following changes in auditory input?
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Could Kcnk15 be involved in auditory processing disorders or hearing impairments?
Addressing these questions could provide valuable insights into both basic auditory neuroscience and potential pathological mechanisms.
Product Specs
Please note: We will prioritize shipping the format currently in stock. However, if you have a specific format requirement, please indicate it in your order notes. We will prepare the product according to your request.
All our proteins are shipped with standard blue ice packs. If you require dry ice shipping, please contact us in advance. Additional fees will apply.
Generally, the shelf life of the liquid form is 6 months at -20°C/-80°C. The shelf life of the lyophilized form is 12 months at -20°C/-80°C.
Target Background
Q&A
What is Potassium Channel Subfamily K Member 15 (Kcnk15)?
Potassium channel subfamily K member 15 (Kcnk15) is a protein encoded by the Kcnk15 gene in rats (human homolog: KCNK15). It belongs to the superfamily of potassium channel proteins containing two pore-forming P domains (K2P channels). Specifically, Kcnk15 encodes K2P15.1, which is part of the acid-sensitive subfamily of K2P channels, also known as TASK-5 (TWIK-related acid-sensitive K+ channel 5) . Unlike many other potassium channels, TASK-5 has historically been considered non-functional when expressed alone, suggesting it requires interaction with other proteins for proper functionality .
How does Kcnk15 differ from other members of the potassium channel subfamily K?
Kcnk15 (TASK-5) is distinct among K2P channels because it has long been considered a non-functional or "silent" channel when expressed alone as a homodimer . Recent research indicates that unlike other fully functional K2P channels, TASK-5 requires heterodimerization with related channels like TASK-1 and TASK-3 to form functional channel complexes . This characteristic distinguishes it from most other potassium channels that can form functional homodimers. Additionally, TASK-5 negatively modulates the surface expression of other TASK channels, suggesting a regulatory role that may be unique within the K2P family .
What is known about the tissue-specific expression of Kcnk15 in rats?
While the search results don't provide comprehensive tissue expression data for rat Kcnk15, research indicates that K2P channels generally show tissue-specific expression patterns. In humans, KCNK15 expression has been found to be altered in various cancer types, including hepatocellular carcinoma (HCC) where it is downregulated . For rat-specific expression patterns, researchers should conduct tissue panel RT-qPCR or consult tissue-specific transcriptome databases. When studying expression patterns, it's crucial to use specific primers that distinguish Kcnk15 from other closely related K2P family members.
How can I evaluate Kcnk15 expression levels in experimental samples?
Evaluation of Kcnk15 expression can be performed using several complementary techniques:
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RT-qPCR: Design specific primers targeting unique regions of Kcnk15 mRNA to quantify transcript levels
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Western blot: Use specific antibodies against Kcnk15 to detect protein expression
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In situ hybridization (ISH): For tissue localization studies, design digoxin-labeled Kcnk15 probes to visualize expression in tissue sections
For rigorous expression analysis, researchers should implement all three methods to confirm both mRNA and protein expression levels. When reporting results, include appropriate housekeeping genes or proteins as controls for normalization.
What functional assays are appropriate for studying recombinant Kcnk15?
Due to the unique characteristics of Kcnk15/TASK-5, appropriate functional assays include:
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Electrophysiology: Patch-clamp recordings remain the gold standard for functional characterization but may require co-expression with TASK-1 or TASK-3 to observe channel activity
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Heterodimer formation assays: Co-immunoprecipitation or FRET-based approaches to detect interactions with other TASK family members
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Surface expression analysis: Biotinylation assays or confocal microscopy to assess membrane localization, especially in the presence of other TASK channels
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Luciferase reporter assays: To investigate regulatory effects on translation, as shown with KCNK15-AS1 interactions
When designing experiments, remember that Kcnk15 homodimers may not yield functional channels, so co-expression with potential partners is essential for comprehensive characterization.
What are the optimal conditions for expressing recombinant rat Kcnk15 in vitro?
For successful expression of recombinant rat Kcnk15:
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Expression system selection: Mammalian cell lines (HEK293, CHO) typically provide better protein folding and processing for ion channels than bacterial systems
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Vector design: Include appropriate tags (His, FLAG) for purification and detection without disrupting channel function
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Storage conditions: Store purified protein at -20°C in Tris-based buffer with 50% glycerol to maintain stability
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Working concentration: Use aliquots at 4°C for up to one week to avoid repeated freeze-thaw cycles
For functional studies, co-expression with TASK-1 or TASK-3 is recommended since Kcnk15 alone may not form functional channels .
How should researchers approach the challenge of Kcnk15's "silent" channel nature?
To address the historically "silent" nature of Kcnk15/TASK-5:
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Heterodimer formation strategy: Express Kcnk15 alongside TASK-1 or TASK-3 to form functional heteromeric channels
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Tandem construct approach: Generate tandem constructs linking Kcnk15 with another TASK family member to force heterodimer formation
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Regulatory protein co-expression: Test co-expression with non-pore-forming proteins that might enable channel function
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Pharmacological profiling: Test responses to known K2P channel modulators in both homodimeric and heterodimeric configurations
Document all experimental conditions meticulously, as subtle differences in expression systems or recording conditions might influence channel functionality.
How do TASK-5/Kcnk15 heterodimers differ functionally from TASK-1 or TASK-3 homodimers?
Recent research has revealed that TASK-5/Kcnk15 forms functional heterodimers with TASK-1 and TASK-3, exhibiting distinct properties:
| Property | TASK-1 Homodimer | TASK-3 Homodimer | TASK-5/TASK-1 Heterodimer | TASK-5/TASK-3 Heterodimer |
|---|---|---|---|---|
| Single-channel conductance | Reference value | Reference value | Altered compared to homodimers | Altered compared to homodimers |
| Gq-coupled receptor inhibition | Present | Present | Modified sensitivity | Modified sensitivity |
| Pharmacological profile | Standard profile | Standard profile | Unique profile affected by KCNK15 polymorphisms | Unique pharmacology |
| Surface expression | Normal | Normal | Reduced (TASK-5 negatively modulates) | Reduced (TASK-5 negatively modulates) |
These functional differences suggest TASK-5 may serve as an endogenous regulator of TASK channel activity through heterodimer formation .
What is the relationship between Kcnk15 and its antisense RNA (Kcnk15-AS1)?
Kcnk15-AS1 is a long non-coding RNA that has a complex regulatory relationship with Kcnk15:
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Kcnk15-AS1 binds directly to the 5'UTR of Kcnk15 mRNA
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This binding inhibits the translation of Kcnk15 without affecting mRNA levels
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In pancreatic cancer cells, Kcnk15-AS1 acts as a tumor suppressor, partly through this regulatory mechanism
For comprehensive understanding of Kcnk15 regulation, researchers should investigate both the protein-coding gene and its antisense RNA partner. Experimental approaches might include RNA immunoprecipitation, dual luciferase reporter assays with the 5'UTR, and overexpression/knockdown studies of Kcnk15-AS1 .
What role does Kcnk15/TASK-5 play in disease contexts?
Emerging evidence links Kcnk15/TASK-5 to several disease contexts:
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Hepatocellular carcinoma (HCC): KCNK15 is significantly downregulated in HCC tissues, with an area under the ROC curve of 0.298248 (p<0.00001), suggesting potential as a diagnostic biomarker
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Pancreatic cancer: Through its interaction with Kcnk15-AS1, Kcnk15 may be involved in pancreatic cancer progression
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Other malignancies: The recent discovery of functional heterodimers opens new avenues for studying TASK-5 in cancers associated with KCNK15 alterations
Research approaches should consider both expression level changes and functional alterations of Kcnk15 in disease states, as well as potential therapeutic implications of targeting this channel or its regulatory partners.
How should researchers interpret contradictory data regarding Kcnk15 functionality?
The long-standing classification of Kcnk15/TASK-5 as a "silent" channel has been challenged by recent findings demonstrating heterodimer functionality. When encountering contradictory data:
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Expression context analysis: Carefully document the expression system, cell type, and co-expressed proteins
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Methodological differences: Consider differences in electrophysiological recording conditions, including temperature, pH, and ionic composition
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Protein partnerships: Evaluate the presence of potential heterodimer partners or regulatory proteins in your experimental system
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Technical validation: Use multiple methodologies to confirm functional or non-functional status
The recent paradigm shift regarding TASK-5 functionality highlights the importance of revisiting established concepts with new experimental approaches .
What statistical approaches are most appropriate for analyzing Kcnk15 expression data in cancer studies?
Based on published research on KCNK15 in cancer contexts, appropriate statistical approaches include:
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ROC curve analysis: Used to evaluate diagnostic potential of Kcnk15 expression, as shown in HCC studies where KCNK15 had an area of 0.298248 with high statistical significance (p<0.00001)
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Kaplan-Meier survival analysis: To correlate Kcnk15 expression levels with patient outcomes
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Multiple comparison corrections: Apply methods like Bonferroni correction when testing multiple KCNK family members
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Multivariate analysis: To control for confounding variables when assessing the independent prognostic value of Kcnk15
When reporting statistical results, include complete statistical parameters (test statistics, degrees of freedom, exact p-values) rather than simplified significance indicators.
What are the most promising unexplored areas of Kcnk15/TASK-5 research?
Several high-potential research directions for Kcnk15/TASK-5 include:
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Comprehensive heterodimer mapping: Systematic investigation of potential heterodimer partners beyond TASK-1 and TASK-3
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Physiological roles of heterodimers: Identification of tissues where TASK-5 heterodimers play significant functional roles
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Structural biology: Cryo-EM or crystallography studies of TASK-5 heterodimers to understand the structural basis of their unique properties
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Polymorphism effects: Investigation of how common polymorphisms in KCNK15 affect heterodimer pharmacology and function
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Therapeutic targeting: Development of compounds specifically targeting TASK-5-containing heterodimers for cancer therapy
These directions recognize the paradigm shift from viewing TASK-5 as non-functional to understanding its role in forming functionally distinct heterodimeric channels.
How might advances in gene editing technologies facilitate Kcnk15 research?
CRISPR-Cas9 and other advanced gene editing technologies offer powerful approaches for Kcnk15 research:
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Knockin of tagged variants: Introduction of fluorescent or epitope tags at endogenous loci to track native expression
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Domain swapping: Precise replacement of channel domains to identify regions critical for heterodimer formation
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Polymorphism modeling: Introduction of specific human polymorphisms into rat Kcnk15 to study their functional consequences
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Conditional expression systems: Development of inducible Kcnk15 expression models to study temporal aspects of channel function
When designing gene editing approaches, consider potential off-target effects and validate edited cells using both sequencing and functional assays.
