PTPN12 is an important tumor suppressor that plays critical roles in various physiological processes. However, the molecular basis underlying the substrate specificity of PTPN12 remains uncertain. Here, enzymological and crystallographic studies have enabled us to identify two distinct structural features that are crucial determinants of PTPN12 substrate specificity: the pY+1 site binding pocket and specific basic charged residues along its surface loops. Key structurally plastic regions and specific residues in PTPN12 enabled recognition of different HER2 phosphorylation sites and regulated specific PTPN12 functions. In addition, the structure of PTPN12 revealed a CDK2 phosphorylation site in a specific PTPN12 loop. Taken together, our results not only provide the working mechanisms of PTPN12 for desphosphorylation of its substrates but will also help in designing specific inhibitors of PTPN12.
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Antioxid Redox Signal
January 2025
Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
Type 2 diabetes as a world-wide epidemic is characterized by the insulin resistance concomitant to a gradual impairment of β-cell mass and function (prominently declining insulin secretion) with dysregulated fatty acids (FAs) and lipids, all involved in multiple pathological development. Recently, redox signaling was recognized to be essential for insulin secretion stimulated with glucose (GSIS), branched-chain keto-acids, and FAs. FA-stimulated insulin secretion (FASIS) is a normal physiological event upon postprandial incoming chylomicrons.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA.
Enzyme engineering is limited by the challenge of rapidly generating and using large datasets of sequence-function relationships for predictive design. To address this challenge, we develop a machine learning (ML)-guided platform that integrates cell-free DNA assembly, cell-free gene expression, and functional assays to rapidly map fitness landscapes across protein sequence space and optimize enzymes for multiple, distinct chemical reactions. We apply this platform to engineer amide synthetases by evaluating substrate preference for 1217 enzyme variants in 10,953 unique reactions.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Biology, University of Konstanz, Konstanz, Germany.
Phosphorylation of substrates by cyclin-dependent kinases (CDKs) is the driving force of cell cycle progression. Several CDK-activating cyclins are involved, yet how they contribute to substrate specificity is still poorly understood. Here, we discover that a positively charged pocket in cyclin B1, which is exclusively conserved within B-type cyclins and binds phosphorylated serine- or threonine-residues, is essential for correct execution of mitosis.
View Article and Find Full Text PDFJ Neurosci Methods
January 2025
Department of Pharmacology, University of the Basque Country, UPV/EHU, Leioa, Spain; BioBizkaia Health Research Institute, Barakaldo, Spain; Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, ISCIII, Spain. Electronic address:
Background: Histone deacetylase (HDAC) density and activity are altered in different brain disorders. Antipsychotic drugs (APs) might modulate HDAC activity in brains of schizophrenia subjects.
New Method: HDAC activity assay amenable for enzyme kinetics and HDAC inhibitor (HDACi) screening studies in postmortem human brain samples.
RNA Biol
December 2025
Department of Cell and Molecular Biology, Biomedical Centre, Uppsala University, Uppsala, Sweden.
We show that a small biotin-binding RNA aptamer that folds into a pseudoknot structure acts as a substrate for bacterial RNase P RNA (RPR) with and without the RNase P C5 protein. Cleavage in the single-stranded region in loop 1 was shown to depend on the presence of a RCCA-motif at the 3' end of the substrate. The nucleobase and the 2'hydroxyl at the position immediately 5' of the cleavage site contribute to both cleavage efficiency and site selection, where C at this position induces significant cleavage at an alternative site, one base upstream of the main cleavage site.
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