The Calcium/Calmodulin-dependent kinase family are serine/threonine kinases which, in general, prefer substrates containing basic residues. Many, but not all, members are regulated by calcium or calmodulin. (Adapted from FBrf0132098).
CASK is thought to be a pseudokinase as it lacks the canonical DFG-motif required for Mg2+-binding in its CaM-kinase domain. In the absence of Mg2+ human CASK was shown to autophosphorylate and to phosphorylate bound neurexin-1 at very low catalytic rate (PMID:18423203). Its inhibition by divalent cations suggests that the kinase is inactive in vivo.