Glycogen synthase kinase 3 (GSK3), a key component of the insulin and wnt signaling pathways, is unusual, as it is constitutively active and is inhibited in response to upstream signals. Kinase activity is thought to be increased by intramolecular phosphorylation of a tyrosine in the activation loop (Y216 in GSK3beta), whose timing and mechanism is undefined. We show that GSK3beta autophosphorylates Y216 as a chaperone-dependent transitional intermediate possessing intramolecular tyrosine kinase activity and displaying different sensitivity to small-molecule inhibitors compared to mature GSK3beta. After autophosphorylation, mature GSK3beta is then an intermolecular serine/threonine kinase no longer requiring a chaperone. This shows that autoactivating kinases have adopted different molecular mechanisms for autophosphorylation; and for kinases such as GSK3, inhibitors that affect only the transitional intermediate would be missed in conventional drug screens.
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http://dx.doi.org/10.1016/j.molcel.2006.10.009 | DOI Listing |
J Opt Soc Am A Opt Image Sci Vis
August 2024
Although second-order surface analyses, mainly mean power and cylinder maps, are commonly used to characterize the progressive addition lens (PAL) surface, recently it has been suggested that third-order variations may also have relevancy in PAL optical and visual performance. This paper proposes a third-order smoothness metric, and its associated Riemannian distance, to further characterize PAL's surface optical performance. These metrics can provide a complementary scoring tool to those classical ones, particularly, to analyze the transition zones between far, near, intermediate, and blending zones.
View Article and Find Full Text PDFJ Chem Phys
January 2025
School of Chemistry, University of Lincoln, Brayford Pool, LN6 7TS Lincoln, United Kingdom.
We analyzed the thermal, structural, and dynamic properties of maghemite using classical molecular dynamics, focusing on bulk and nanoparticle systems. We explored their behavior when heated to high temperatures (above the melting point) and during cooling, as well as under thermal cycles ending at intermediate temperatures. Our findings show that in the bulk system, both the tetrahedral and octahedral iron sub-lattices undergo a phase transition prior to melting.
View Article and Find Full Text PDFEven after folding, proteins transiently sample unfolded or partially unfolded intermediates, and these species are often at risk of irreversible alteration ( via proteolysis, aggregation, or post-translational modification). Kinetic stability, in addition to thermodynamic stability, can directly impact protein lifetime, abundance, and the formation of alternative, sometimes disruptive states. However, we have very few measurements of protein unfolding rates or how mutations alter these rates, largely due to technical challenges associated with their measurement.
View Article and Find Full Text PDFDuring nervous system development, diverse types of neurons and glia are sequentially generated by self-renewing neural stem cells (NSCs). Temporal changes in gene expression within NSCs are thought to regulate neural diversity; however, the mechanisms regulating the timing of these temporal gene transitions remain poorly understood. type II NSCs, like human outer radial glia, divide to self-renew and generate intermediate neural progenitors, amplifying and diversifying the population of neurons innervating the central complex, a brain region required for sensorimotor coordination.
View Article and Find Full Text PDFCytoplasmic dynein is an essential microtubule motor protein that powers organelle transport and mitotic spindle assembly. Its activity depends on dynein-dynactin-cargo adaptor complexes, such as dynein-dynactin-BicD2 (DDB), which typically function with two dynein motors. We show that mechanical tension recruits a third dynein motor via an auxiliary BicD adaptor binding the light intermediate chain of the third dynein, stabilizing multi-dynein assemblies and enhancing force generation.
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