KCNK7

Model summary

A human multi-pass membrane channel that forms a constitutive outwardly rectifying pathway for potassium. Its tandem pore architecture generates background K+ conductance that stabilizes resting membrane potential and shapes cellular excitability. The channel resides at the cell surface, where it assembles with other membrane-associated proteins to tune surface density and activity, thereby sustaining potassium flux that underlies transport and electrical homeostasis.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   Two pore domain potassium channel signatures dominate the sequence: IPR013099 (Potassium channel domain, residues 85–142) and IPR013099 (Potassium channel domain, residues 182–258) mark two K+-selective pore modules arranged in tandem. This tandem arrangement is the hallmark of two-pore domain potassium channels and establishes a K+-selective conduction pathway. The broader channel identity is reinforced by IPR003280 (Two pore domain potassium channel family, residues 8–258) and IPR003092 (Two pore domain potassium channel, TASK family, residues 9–297), which together specify a slow, background K+ conductance module rather than a classical voltage-gated pore. Additional family-level matches—IPR005408 (Two pore domain potassium channel, TWIK family, residues 57–69; 71–87; 239–252; 254–272)—tie the sequence to the TWIK branch of K2P channels, which share conserved transmembrane topologies and cytosolic interaction surfaces. The ordered layout—N-terminal K+-channel family signatures leading into two internal pore domains and TWIK/TASK family hallmarks—causally dictates a constitutively active, background K+ conductance pathway.

2. 02

   From this architecture, the molecular function follows.

   The paired K+-selective pore domains create a permeation pathway that conducts K+ down its electrochemical gradient, which defines GO:0005267 potassium channel activity. The presence of multiple family-level interaction modules and cytosolic-facing surfaces typical of K2P channels supports auxiliary macromolecular contacts, consistent with GO:0005515 protein binding. These binding interfaces enable assembly into membrane microdomains and association with trafficking and scaffolding partners.

3. 03

   The biological process emerges directly from the ion-conduction role.

   A constitutively active K2P channel stabilizes membrane potential by providing outward K+ currents, thereby driving GO:0006813 potassium ion transport. Such sustained K+ flux sets resting membrane potential and shapes cellular excitability and signaling.

4. 04

   Cellular location is inferred from the multi-pass architecture and the need to access extracellular K+ and transmembrane gradients.

   The tandem pore arrangement requires a lipid bilayer environment, and the experimentally supported placement is the cell surface, aligning with GO:0005886 plasma membrane. The multi-pass nature and pore modules further imply an integral membrane residency.

5. 05

   Mechanistically, the tandem pore architecture forms a constitutive K+-selective conduit that operates without classical gating.

   The two pore loops and their selectivity filters assemble a central conduction pathway whose slow activation and deactivation yield background conductance. Cytosolic N- and C-terminal tails likely mediate assembly and trafficking, explaining protein-binding capacity and membrane residency. I hypothesize that the channel oligomerizes with other K2P subunits and associates with membrane scaffolds and trafficking adaptors. Likely partners include TASK and TWIK family members that form heterotetrameric assemblies, as well as plasma-membrane scaffolds and endocytic adaptors that tune surface density and localization. Together, these interactions stabilize a resting-potential module at the plasma membrane that continuously extrudes K+ to set cellular excitability thresholds.