Molecular motor kinesins move processively along microtubules by using energy derived from ATP hydrolysis. Almost all of the intermediate structures of this ATPase reaction cycle have been solved for the monomeric kinesin KIF1A. Based on this structural information, we present here the common atomic mechanisms of kinesin motility, which can be applied not only to the monomeric kinesins but also to the dimeric kinesins. Structural studies have suggested that kinesins accomplish their mission by utilizing the evolutionary conserved strategy among the various ATPases/GTPases/kinases in which they use the energy from the ATP/GTP hydrolysis to attach/detach to/from their effectors.
The Spemann organizer secretes the anti-BMP protein Chd, and provides dorsal positional information by inactivating the ventralizing signals BMPs in a spatially graded manner. Several studies have shown that a morphogenetic field exhibits a strong tendency of self-regulation. For instance, when a blastula embryo is bisected across the D-V axis, the dorsal half develops into a well-proportioned half-size embryo, which retains a nearly normal DV ratio. These observations indicate that the BMP activity gradient is dynamically and flexibly regulated in response to changes of the embryonic size. Here we demonstrate that the auto-regulatory loop of Chd degradation plays a decisive role in scaling.
Although several methods of in vitro directed evolution have been developed, they were applied to globular proteins, but not to membrane proteins. Liposome display is a novel method, which enables the directed evolution of membrane protein in vitro. Membrane protein was synthesized by the cell-free translation system in a cell-sized liposome, and its function was probed by a fluorescence indicator. Liposome with high fluorescence intensity was selected by a cell sorter, enabling the isolation of DNA encoding the evolved protein. Here, we show the application of this method to α-hemolysin, one of the membrane proteins from Staphylococcus aureus.
Receptor tyrosine kinase is a membrane protein that regulates cell growth and differentiation. Ligand binding to the extracellular region triggers its function as a kinase in the intracellular region. Yet, it is still not known how the “signal” encoded by ligand binding to the receptor is transmitted across the membrane. Answering this fundamental question requires analysis in detail on the transmembrane and the juxtamembrane regions of the receptor. This review focuses on recent progress in structural work for these regions to understand the activation mechanism of EGFR, arguably one of the most intensively studied membrane receptors.
We have recently studied the thermotropic phase behavior of cholesterol-containing binary bilayers of a homologous series of linear saturated phosphatidylcholines (CnPCs) with different hydrocarbon-chain lengths n (n = 14-18) using the Prodan fluorescence spectroscopy and differential scanning calorimetry to construct temperature-composition phase diagrams for those binary bilayers. This review describes our concept on the miscibility between cholesterol and CnPC on the basis of the experimental phase diagrams as well as the distribution of cholesterol within the bilayers derived by applying the so-called superlattice model.