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Unlabelled: Vitamin B (cobalamin) is a high-value yet scarce cofactor required for various metabolic processes, making its efficient handling important for maintaining metabolic homeostasis. While the involvement of ATP:cob(I)alamin adenosyltransferases (MMAB) in the synthesis, delivery, and repair of 5'-deoxyadenosylcobalamin (AdoCbl) is well established, the kinetic mechanisms that regulate this process, particularly its negative cooperativity, remain poorly understood. Understanding these mechanisms is key to clarifying how MMAB efficiently uses AdoCbl, prevents resource wastage, and supports bacterial survival in nutrient-limited environments.
View Article and Find Full Text PDFUnlabelled: Myosin-IC (myo1c) is a class-I myosin that supports transport and remodeling of the plasma membrane and membrane-bound vesicles. Like other members of the myosin family, its biochemical kinetics are altered in response to changes in mechanical loads that resist the power stroke. However, myo1c is unique in that the primary force-sensitive kinetic transition is the isomerization that follows ATP binding, not ADP release as in other slow myosins.
View Article and Find Full Text PDFJ Mol Biol
January 2025
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA. Electronic address:
The mammalian cell cycle is coordinated by primarily four cyclin-dependent kinases (CDKs), which are activated by a family of cyclin proteins to phosphorylate diverse protein effectors of cell growth and division. A wealth of qualitative protein interaction studies have supported a model in which different CDKs have specific cognate cyclin partners. However, there have been few quantitative measurements of binding kinetics and affinity to support our understanding of CDK-cyclin preferences and the structural origins of those preferences.
View Article and Find Full Text PDFACS Synth Biol
January 2025
Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California 94702, United States.
Naturally evolved and synthetically designed forms of compartmentalization benefit encapsulated function by increasing local concentrations of substrates and protecting cargo from destabilizing environments and inhibitors. Crucial to understanding the fundamental principles of compartmentalization are experimental systems enabling the measurement of the permeability rates of small molecules. Here, we report the experimental measurement of the small-molecule permeability of a 40 nm icosahedral bacterial microcompartment shell.
View Article and Find Full Text PDFActa Physiol (Oxf)
February 2025
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
Aim: Somatostatin from pancreatic δ-cells is a paracrine regulator of insulin and glucagon secretion, but the release kinetics and whether secretion is altered in diabetes is unclear. This study aimed to improve understanding of somatostatin secretion by developing a tool for real-time detection of somatostatin release from individual pancreatic islets.
Methods: Reporter cells responding to somatostatin with cytoplasmic Ca concentration ([Ca]) changes were generated by co-expressing somatostatin receptor SSTR2, the G-protein Gα15 and a fluorescent Ca sensor in HeLa cells.
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