In molecular biology, calmodulin binding domain (CaMBD) is a

protein domain In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of ...

found in small-conductance calcium-activated potassium channels (

SK channel SK channels (small conductance calcium-activated potassium channels) are a subfamily of calcium-activated potassium channels. They are so called because of their small single channel conductance in the order of 10 pS. SK channels are a type of i ...

s). These channels are independent of

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...

and gated solely by

intracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions ...

Ca²⁺. They are

heteromeric A heteromer is something that consists of different parts; the antonym of homomeric. Examples are: Biology * Spinal neurons that pass over to the opposite side of the spinal cord. * A protein complex that contains two or more different polypeptid ...

complexes that comprise pore-forming alpha-subunits and the Ca²⁺-binding

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

calmodulin (CaM). CaM

bind BIND () is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named (pronounced ''name-dee'': , short for ''name daemon''), performs both of the main DNS server roles, acting as an authoritative ...

s to the SK channel through the CaMBD, which is located in an

region of the alpha-subunit immediately carboxy-terminal to the pore. Channel opening is triggered when Ca²⁺ binds the EF hands in the N-lobe of CaM. The structure of this domain complexed with CaM is known. This domain forms an elongated

dimer Dimer may refer to: * Dimer (chemistry), a chemical structure formed from two similar sub-units ** Protein dimer, a protein quaternary structure ** d-dimer * Dimer model, an item in statistical mechanics, based on ''domino tiling'' * Julius Dimer ...

with a CaM

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

bound at each end; each CaM wraps around three

alpha-helices The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...

, two from one CaMBD subunit and one from the other.

References

{{InterPro content, IPR004178 Protein families