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C-terminal kinase associated domain 1 (KA1) of Maternal embryonic leucine zipper kinase MELK, also called protein kinase 38 (PK38) or pEg3 kinase, is a cell cycle-regulated serine/threonine protein kinase (STK) that catalyzes the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. It is phosphorylated and maximally active during mitosis and is involved in regulating cell cycle progression, division, proliferation, tumor growth, and mRNA splicing. MELK shows a broad substrate specificity, including the zinc finger-like protein ZPR9, the transcription and splicing factor NIPP1, and the protein-tyrosine phosphatase Cdc25B, among others. MELK contains an N-terminal catalytic domain followed by a ubiquitin-associated (UBA) domain, a TP dipeptide-rich region, and a C-terminal KA1 domain. The KA1 domain of MELK, together with its TP dipeptide-rich region, functions as an autoinhibitory domain. The KA1 domain of the related microtubule affinity-regulating kinases (MARKs) has been shown to bind anionic phospholipids and may be involved in membrane localization. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",