Figure 1.

Sequence alignment of the human small conductance Ca²⁺-activated K⁺ channels hSK1, hSK2 and hSK3. The putative transmembrane spanning regions, S1–S6, are boxed in gray. The pore region (P-Region) is boxed in turquoise. The calmodulin-binding domain (CaMBD) is indicated by black bars. Amino acids corresponding to phosphorylation consensus sequences for the cyclic AMP- and cyclic GMP-dependent kinases (PKA and PKG) are displayed in red, for protein kinase C (PKC) in blue; and for casein kinase 2 (CK2) boxed in orange. Only intracellular phosphorylation consensus sequences have been labeled for PKA, PKG and PKC, while both intra- and extracellular ones have been highlighted for CK2 because of its potential action as an endo- and ectokinase [263]. Phosphorylation consensus sites have been mapped using the Prosite database: for PKA/PKG: PS00004: [RK](2)-x-[ST]; for PKC: PS00005: [ST]-x-[RK]; for CK2: PS00006: [ST]-x(2)-[DE].