CDC42BPB/MRCKb

MRCK beta (CDC42BPB) is the paralogue of MRCK alpha and the second CDC42-binding kinase of the DMPK family. Like its sibling it couples to GTP-bound CDC42 through a C-terminal CRIB-like motif, releasing an autoinhibited coiled-coil tail so that the kinase can phosphorylate myosin regulatory light chain and MYPT1. The two isoforms overlap in contractility control but differ in tissue distribution and in the coiled-coil region that governs partner binding, and MRCK beta has been singled out for roles in endothelial permeability, tumour cell invasion and neuronal morphology. Recombinant MRCK beta is used alongside MRCK alpha to resolve isoform-specific functions and to screen dual or selective inhibitors of this branch.