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Catalytic domain of the Serine/Threonine kinase, Leucine-Rich Repeat Kinase STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. LRRKs are also classified as ROCO proteins because they contain a ROC (Ras of complex proteins)/GTPase domain followed by a COR (C-terminal of ROC) domain of unknown function. In addition, LRRKs contain a catalytic kinase domain and protein-protein interaction motifs including a WD40 domain, LRRs and ankyrin (ANK) repeats. LRRKs possess both GTPase and kinase activities, with the ROC domain acting as a molecular switch for the kinase domain, cycling between a GTP-bound state which drives kinase activity and a GDP-bound state which decreases the activity. Vertebrates contain two members, LRRK1 and LRRK2, which show complementary expression in the brain. Mutations in LRRK2 are linked to both familial and sporadic forms of Parkinson's disease. The normal roles of LRRKs are not clearly defined. They may be involved in mitogen-activated protein kinase (MAPK) pathways, protein translation control, programmed cell death pathways, and cytoskeletal dynamics. The LRRK subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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