In molecular biology, calmodulin binding domain (CaMBD) is a protein domain found in small-conductance calcium-activated potassium channels (SK channels).

These channels are independent of voltage and gated solely by intracellular Ca2+.

They are heteromeric complexes that comprise pore-forming alpha-subunits and the Ca2+-binding protein calmodulin (CaM).

[1] CaM binds to the SK channel through the CaMBD, which is located in an intracellular 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.