C-terminal regulatory domain of 5'-AMP-activated protein kinase (AMPK) alpha subunit and similar domains
This family is composed of AMPKs, microtubule-associated protein/microtubule affinity regulating kinases (MARKs), yeast Kcc4p-like proteins, plant calcineurin B-Like (CBL)-interacting protein kinases (CIPKs), and similar proteins. They are serine/threonine protein kinases (STKs) that catalyze the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. AMPKs act as sensors for the energy status of the cell and are activated by cellular stresses that lead to ATP depletion such as hypoxia, heat shock, and glucose deprivation, among others. MARKs phosphorylate the tau protein and related microtubule-associated proteins (MAPs) on tubulin binding sites to induce detachment from microtubules, and are involved in the regulation of cell shape and polarity, cell cycle control, transport, and the cytoskeleton. Kcc4p and related proteins are septin-associated proteins that are involved in septin organization and in the yeast morphogenesis checkpoint coordinating the cell cycle with bud formation. CIPKs interact with the calcineurin B-like (CBL) calcium sensors to form a signaling network that decode specific calcium signals triggered by a variety of environmental stimuli including salinity, drought, cold, light, and mechanical perturbation, among others. All members of this family contain an N-terminal catalytic kinase domain and a C-terminal regulatory domain which is also called kinase associated domain 1 (KA1) in some cases. The C-terminal regulatory domain serves as a protein interaction domain in AMPKs and CIPKs. In MARKs and Kcc4p-like proteins, this domain binds phospholipids and may be involved in membrane localization.