5,879 research outputs found
CARD8 and NLRP1 Undergo Autoproteolytic Processing through a ZU5-Like Domain
The âFunction to Find Domainâ (FIIND)-containing proteins CARD8 (Cardinal; Tucan) and NLRP1 (NALP1; NAC) are well known components of inflammasomes, multiprotein complexes responsible for activation of caspase-1, a regulator of inflammation and innate immunity. Although identified many years ago, the role of the FIIND is unknown. Here, we report that CARD8 and NLRP1 undergo autoproteolytic cleavage at a conserved SF/S motif within the FIIND. Using bioinformatics and computational modeling approaches, we detected striking structural similarity between the FIIND and the ZU5-UPA domain present in the autoproteolytic protein PIDD. This allowed us to generate a three-dimensional model and to gain insights in the molecular mechanism of the cleavage. Site-directed mutagenesis experiments revealed that the second serine of the SF/S motif is required for CARD8 and NLRP1 autoproteolysis. Furthermore, we discovered an important function for conserved glutamic acid and histidine residues, located in proximity of the cleavage site in regulating the autoprocessing efficiency. Altogether, these results identify a function for the FIIND and show that CARD8 and NLRP1 are ZU5-UPA domain-containing autoproteolytic proteins, thus suggesting a novel mechanism for regulating innate immune responses
Stratigraphic studies of Ganymede's tectonic activity in the bright terrain: results from the Byblus Sulcus and Harpagia Sulcus regions
Modeling nuclei of radio galaxies from VLBI radio observations. Application to the BL Lac Object S5 1803+784
We present a new method to fit the variations of both coordinates of a VLBI
component as a function of time, assuming that the nucleus of the radio source
contains a binary black hole system (BBH system). The presence of a BBH system
produces 2 perturbations of the trajectory of the ejected VLBI components. By
using only the VLBI coordinates, the problem we have to solve reduces to an
astrometric problem. Knowledge of the variations of the VLBI coordinates as a
function of time contains the kinematical information, thus we are able to
deduce the inclination angle of the source and the bulk Lorentz factor of the
ejected component. Generally, there is a family of the BBH system producing the
same fit to our data. To illustrate this method, we apply it to the source
1807+784. We find that the inclination of the source is i = 5.8+-1.8 degrees
and the VLBI component is ejected with a bulk Lorentz factor of 3.7+-0.3. We
determine the family of the BBH system which provides the best fit, assuming at
first that the masses of the 2 black holes are equal and then that the masses
are different. Each family of BBH systems is characterized by Tp/Tb~1.967,
where Tp and Tb are the precession period of the accretion disk of the black
hole ejecting the VLBI component and the orbiting period of the BBH system.Comment: 15 pages, 12 figure
Optimization of Convex Risk Functions
We consider optimization problems involving convex risk functions. By employing techniques of convex analysis and optimization theory in vector spaces of measurable functions we develop new representation theorems for risk models, and optimality and duality theory for problems involving risk functions
Stratigraphic relationships of different terrain units on Ganymede and possible implications towards their evolution
The kinematics in the pc-scale jets of AGN The case of S5 1803+784
We present a kinematic analysis of jet component motion in the VLBI jet of
the BL Lac object S5 1803+784, which does not reveal long-term outward motion
for most of the components. Understanding the complex kinematic phenomena can
possibly provide insights into the differences between quasars and BL Lac
objects. The blazar S5 1803+784 has been studied with VLBI at =1.6, 2.3,
5, 8.4, and 15 GHz between 1993.88 and 2005.68 in 26 observing runs. We
(re)analyzed the data and present Gaussian model-fits. We collected the already
published kinematic information for this source from the literature and
re-identified the components according to the new scenario presented in this
paper. Altogether, 94 epochs of observations have been investigated. A careful
study of the long-term kinematics reveals a new picture for component motion in
S5 1803+784. In contrast to previously discussed motion scenarios, we find that
the jet structure within 12 mas of the core can most easily be described by the
coexistence of several bright jet features that remain on the long-term at
roughly constant core separations (in addition to the already known {\it
stationary} jet component 1.4 mas) and one faint component moving with
an apparent superluminal speed ( 19c, based on 3 epochs). While most of
the components maintain long-term roughly constant distances from the core, we
observe significant, smooth changes in their position angles. We report on an
evolution of the whole jet ridge line with time over the almost 12 years of
observations. The width of the jet changes periodically with a period of
8 to 9 years. We find a correlation between changes in the position angle and
maxima in the total flux-density. We present evidence for a geometric origin of
the phenomena and discuss possible models.Comment: The manuscript will be published by A&
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