The phosphorylation and dephosphorylation of proteins on serine and threonine residues is an essential means of regulating a broad range of cellular functions in eukaryotes, including cell division, homeostasis and apoptosis. ?-protein kinase 1, also known as ALPK1, LAK or KIAA1527, is a 1,244 amino acid protein that contains one ?-type protein kinase domain and belongs to the protein kinase superfamily. Expressed at high levels in liver, ?-protein kinase 1 recognizes and phosphorylates specific phosphorylation sites that are surrounded by peptides which have an å-helical conformation. One of the targets of å-protein kinase 1 is Myosin I and, via its ability to phosphorylate Myosin I, ?-protein kinase 1 is thought to play an important role in the apical trafficking of vesicles carrying raft-associated sucrase-isomaltase (SI).