Two tandem repeats of the cystathionine beta-synthase (CBS pair) domains associated with the voltage gated CLC (chloride channel) in eukaryotes and bacteria
This cd contains two tandem repeats of the cystathionine beta-synthase (CBS pair) domains associated with the voltage gated CLC voltage-gated chloride channel. The CBS pairs here are found in the EriC CIC-type chloride channels in eukaryotes and bacteria. These ion channels are proteins with a seemingly simple task of allowing the passive flow of chloride ions across biological membranes. CIC-type chloride channels come from all kingdoms of life, have several gene families, and can be gated by voltage. The members of the CIC-type chloride channel are double-barreled: two proteins forming homodimers at a broad interface formed by four helices from each protein. The two pores are not found at this interface, but are completely contained within each subunit, as deduced from the mutational analyses, unlike many other channels, in which four or five identical or structurally related subunits jointly form one pore. The CBS domain, named after human CBS, is a small domain originally identified in cystathionine beta-synthase and is subsequently found in a wide range of different proteins. CBS domains usually occur in tandem repeats. They associate to form a so-called Bateman domain or a CBS pair based on crystallographic studies in bacteria. The CBS pair was used as a basis for this cd hierarchy since the human CBS proteins can adopt the typical core structure and form an intramolecular CBS pair. The interface between the two CBS domains forms a cleft that is a potential ligand binding site. The CBS pair coexists with a variety of other functional domains and this has been used to help in its classification here. It has been proposed that the CBS domain may play a regulatory role, although its exact function is unknown. Mutations of conserved residues within this domain are associated with a variety of human hereditary diseases, including congenital myotonia, idiopathic generalized epilepsy, hypercalciuric nephrolithiasis, and classic Bartter syndrome (CLC chloride channel family members), Wolff-Parkinson-White syndrome (gamma 2 subunit of AMP-activated protein kinase), retinitis pigmentosa (IMP dehydrogenase-1), and homocystinuria (cystathionine beta-synthase).
Jiyao W et al.(2023). "The conserved domain database in 2023.",