Human urokinase-type-plasminogen-activator receptor (uPAR) is a glycolipid-anchored membrane glycoprotein comprising three structurally similar domains. We have succeeded in direct observation of the ternary complex formation of single-chain urokinase (scuPA) or its N-terminal fragment (ATF) with the separated domain-1 (N-terminal domain) and domain-(2ϩ3) (internal and C-terminal domain) of human uPAR, by means of gel-filtration HPLC analysis. This complex was found to consist of the three components in an equimolar ratio (thus referred to as the three-part complex). To determine the nature of the interaction between these components, cross-linking experiments involving various kinds of crosslinkers and competitive binding assay on ELISA were performed. These experiments have shown that each uPAR domain can bind directly to scuPA at low affinity, and that both these domains contribute to the high-affinity binding between scuPA and uPAR in a synergistic manner. It can be considered that the synergistic effect of domain-1 and domain-(2ϩ3) on scuPA binding would result from a conformational change, and that this steric event might trigger the signal transduction reported for scuPA/uPAR binding.
We report the synthesis and optoelectronic
properties of high phase-purity
(>94 mol %) bulk polycrystals of KCoO2-type layered
nitrides AETMN2 (AE =
Sr, Ba; and TM = Ti, Zr, Hf), which are expected
to exhibit unique electron
transport properties originating from their natural two-dimensional
(2D) electronic structure, but high-purity intrinsic samples have
yet been reported. The bulks were synthesized using a solid-state
reaction between AENH and TMN precursors
with NaN3 to achieve high N chemical potential during the
reaction. The AETMN2 bulks are n-type
semiconductors with optical band gaps of 1.63 eV for SrTiN2, 1.97 eV for BaZrN2, and 2.17 eV for BaHfN2. SrTiN2 and BaZrN2 bulks show degenerated
electron conduction due to the natural high-density electron doping
and paramagnetic behavior in all of the temperature ranges examined,
while such unintentional carrier generation is largely suppressed
in BaHfN2, which exhibits nondegenerated electron conduction.
The BaHfN2 sample also exhibits weak ferromagnetic behavior
at temperatures lower than 35 K. Density functional theory calculations
suggest that the high-density electron carriers in SrTiN2 come from oxygen impurity substitution at the N site (ON) acting as a shallow donor even if the high-N chemical potential
synthesis conditions are employed. On the other hand, the formation
energy of ON becomes larger in BaHfN2 because
of the stronger TM–N chemical bonds. Present
results demonstrate that the easiness of impurity incorporation is
designed by density functional calculations to produce a more intrinsic
semiconductor in wider chemical conditions, opening a way to cultivating
novel functional materials that are sensitive to atmospheric impurities
and defects.
Surcophaga lectin is a defence protein synthesized by the fat body and secreted into the hemolymph in response to injury of the body of third instar larvae of Surcophugu peregrina (flesh-fly). In this paper, we demonstrate that the stimulus of body injury is first transmitted to a certain tissue present in the anterior part of the body, and from there a mediator molecule that interacts directly with fat body cells is secreted into the hemolymph. On interaction with this mediator molecule, the fat body begins to synthesize mRNA for Sarcophuga lectin.
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