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Rhodopsin is a light-activated G-protein-coupled receptor. The structure of its ligand-free state at 2.9 Å resolution was reported recently. This paper describes a similar resolution crystal structure of the same protein bound to a fragment of G-protein and suggests a mechanism by which G-proteins might be activated by G-protein-coupled receptors.
Long duration γ-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and provide a window into the process of black hole formation from the collapse of massive stars. Observations of the extraordinarily bright prompt optical and γ-ray emission of GRB 080319B shows that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.
Artificial atoms, quantum systems with atom-like energy structure, have been studied with frequency spectroscopic techniques. However, much information about the energy level spectrum has been hidden, as the technique is impractical for high frequencies. A complementary technique has been developed where the energy level of an artificial atom is not scanned by tuning frequency, but amplitude of the radiation, while the frequency is tuned to a specific feature in the spectrum.
With a comprehensive analysis of sequencing data, DNA copy number, gene expression and DNA methylation in a large number of human glioblastomas, The Cancer Genome Atlas project initiative provides a broad overview of the genes and pathways that are altered in this cancer type.
To prevent the tips of chromosomes from becoming shorter with each round of DNA duplication and cell division, telomerase extends the telomere lagging strand so that it matches the full length of the telomere leading strand. This paper presents the structure of the catalytic subunit of telomerase. By modelling in a hybrid RNA–DNA molecule, it is possible to visualize how the end of the DNA primer is positioned within the enzyme's active site.
This paper shows that exocrine cells of the pancreas can be converted in vivo to insulin-secreting endocrine cells. Interestingly, the transdifferentiating cells did not have to revert to a more primitive, pluripotent state in this process, but seemed to move directly from one differentiated state to another.
ALK is identified as a neuroblastoma predisposition gene. Germline mutations were found in ALK, a tryrosine kinase receptor, in affected families. In addition, somatic point mutations in ALK were found in sporadic cases of neuroblastomas. ALK mutations seem to lead to constitutive activation of its kinase activity and promote cell proliferation.
The genome sequence for Trichoplax adhaerens is analysed, and it is reported that the organism retains many features of the last common ancestor with cnidarians and bilaterians, estimated to be over 600 million years ago. However, T. adhaerens also contains genes for developmental patterns and cell types which have never been seen in this animal, suggesting that we might still not know the full story.