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UBA domain found in salt-inducible kinase SIK1, SIK2, SIK3 and similar proteins Salt-inducible kinase SIK1, SIK2, SIK3 are serine/threonine kinases that belong to the AMP-activated protein kinases (AMPK) family involved in the regulation of metabolism during energy stress. SIK1, also called serine/threonine-protein kinase SNF1-like kinase 1 (SNF1LK), is required for myogenic differentiation. It is degraded by the proteasome in myoblasts which is regulated by cAMP signaling. Moreover, SIK1 acts as a class II histone deacetylase (HDAC) kinase, triggering the cytoplasmic export of the HDACs and activation of myocyte enhancer factor 2 (MEF2)-dependent transcription. It also regulates transcription through inhibitory phosphorylation of a family of cAMP responsive element binding protein (CREB) coactivators, called TORCs/CRTCs. In addition, SIK1 links LKB1 to p53-dependent anoikis and suppresses metastasis. It is also involved in a cell sodium-sensing network that regulates active sodium transport through a calcium-dependent process. SIK2, also called Qin-induced kinase or serine/threonine-protein kinase SNF1-like kinase 2 (SNF1LK2), plays an important role in the insulin-signaling pathway during adipocyte differentiation, as well as in autophagy progression. Moreover, SIK2 plays a critical role in neuronal survival and modulates cAMP responsive element binding protein (CREB)-mediated gene expression in response to hormones and nutrients. SIK2 acts as a critical determinant in autophagy progression. In addition, SIK2 localizes at the centrosome and functions as a centrosome kinase required for bipolar mitotic spindle formation. It is involved in the initiation of mitosis, and regulates the localization of the centrosome linker protein, C-Nap1, through S2392 phosphorylation. SIK3, also called salt-inducible kinase 3 or serine/threonine-protein kinase QSK, acts as a novel energy regulator that modulates cholesterol and bile acid metabolism by coupling with retinoid metabolism. It also play an essential role in facilitating chondrocyte hypertrophy during skeletogenesis and growth plate maintenance. Members in this family contain an N-terminal protein kinase catalytic domain followed by an ubiquitin-associated (UBA) domain. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",