5,653 research outputs found
Role of the unique N-terminal domain of CtBP2 in determining the subcellular localisation of CtBP family proteins
BACKGROUND: CtBP1 and CtBP2 are transcriptional co-repressors that modulate the activity of a large number of transcriptional repressors via the recruitment of chromatin modifiers. Many CtBP-regulated proteins are involved in pathways associated with tumorigenesis, including TGF-beta and Wnt signalling pathways and cell cycle regulators such as RB/p130 and HDM2, as well as adenovirus E1A. CtBP1 and CtBP2 are highly similar proteins, although evidence is emerging that their activity can be differentially regulated, particularly through the control of their subcellular localisation. CtBP2s from diverse species contain a unique N-terminus, absent in CtBP1 that plays a key role in controlling the nuclear-cytoplasmic distribution of the protein.RESULTS: Here we show that amino acids (a.a.) 4-14 of CtBP2 direct CtBP2 into an almost exclusively nuclear distribution in cell lines of diverse origins. Whilst this sequence contains similarity to known nuclear localisation motifs, it cannot drive nuclear localisation of a heterologous protein, but rather has been shown to function as a p300 acetyltransferase-dependent nuclear retention sequence. Here we define the region of CtBP2 required to co-operate with a.a. 4-14 to promote CtBP2 nuclear accumulation as being within a.a. 1-119. In addition, we show that a.a. 120-445 of CtBP2 can also promote CtBP2 nuclear accumulation, independently of a.a. 4-14. Finally, CtBP1 and CtBP2 can form heterodimers, and we show that the interaction with CtBP2 is one mechanism whereby CtBP1 can be recruited to the nucleus.CONCLUSION: Together, these findings represent key distinctions in the regulation of the functions of CtBP family members that may have important implications as to their roles in development, and cell differentiation and survival.<br/
Conductance fluctuations at the integer quantum Hall plateau transition
We study numerically conductance fluctuations near the integer quantum Hall
effect plateau transition. The system is presumed to be in a mesoscopic regime,
with phase coherence length comparable to the system size. We focus on a
two-terminal conductance G for square samples, considering both periodic and
open boundary conditions transverse to the current. At the plateau transition,
G is broadly distributed, with a distribution function close to uniform on the
interval between zero and one in units of e^2/h. Our results are consistent
with a recent experiment by Cobden and Kogan on a mesoscopic quantum Hall
effect sample.Comment: minor changes, 5 pages LaTex, 7 postscript figures included using
epsf; to be published Phys. Rev. B 55 (1997
Criticality in the two-dimensional random-bond Ising model
The two-dimensional (2D) random-bond Ising model has a novel multicritical
point on the ferromagnetic to paramagnetic phase boundary. This random phase
transition is one of the simplest examples of a 2D critical point occurring at
both finite temperatures and disorder strength. We study the associated
critical properties, by mapping the random 2D Ising model onto a network model.
The model closely resembles network models of quantum Hall plateau transitions,
but has different symmetries. Numerical transfer matrix calculations enable us
to obtain estimates for the critical exponents at the random Ising phase
transition. The values are consistent with recent estimates obtained from
high-temperature series.Comment: minor changes, 7 pages LaTex, 8 postscript figures included using
epsf; to be published Phys. Rev. B 55 (1997
A Scaling-up Synthesis From Laboratory Scale to Pilot Scale and to Near Commercial Scale for Paste-Glue Production
This paper concerns on developing a synthesis method of paste-glue production for gummed tape using a corn-based starch as an alternative feedstock from laboratory-scale to pilot-scale and to near commercial scale. Basically, two methods of synthesis were developed to produce paste-glue in laboratory scale. Based on the two methods, we then scale-up the earlier laboratory scale data to pilot-scale and near commercial-scale for developing a large scale process production of paste-glue. Scaling up production from 1,000 ml reactor to 500 L pilot-scale reactor and 1,500 L near commercial scale reactor, we monitored pathway of temperature increase during reaction as well as adjustment of operating condition conducted for laboratory experimental data in order to produce a good quality of paste-glue. Some scaling up parameters have been found as well as critical parameters for a good product quality such as viscosity and ceiling temperature of the reaction which are very crucial in order to give optimum operating condition. We have selected synthesis method of paste-glue production and found the range of the parameters in order to produce a very good quality of paste-glue in pilot scale and near commercial scale
Risk Factors and In-Hospital Outcomes following Tracheostomy in Infants
To describe the epidemiology, risk factors, and in-hospital outcomes of tracheostomy in infants in the neonatal intensive care unit (NICU)
Numerical evidence for `multi-scalar stars'
We present a class of general relativistic soliton-like solutions composed of
multiple minimally coupled, massive, real scalar fields which interact only
through the gravitational field. We describe a two-parameter family of
solutions we call ``phase-shifted boson stars'' (parameterized by central
density rho_0 and phase delta), which are obtained by solving the ordinary
differential equations associated with boson stars and then altering the phase
between the real and imaginary parts of the field. These solutions are similar
to boson stars as well as the oscillating soliton stars found by Seidel and
Suen [E. Seidel and W.M. Suen, Phys. Rev. Lett. 66, 1659 (1991)]; in
particular, long-time numerical evolutions suggest that phase-shifted boson
stars are stable. Our results indicate that scalar soliton-like solutions are
perhaps more generic than has been previously thought.Comment: Revtex. 4 pages with 4 figures. Submitted to Phys. Rev.
Persistence and Quiescence of Seismicity on Fault Systems
We study the statistics of simulated earthquakes in a quasistatic model of
two parallel heterogeneous faults within a slowly driven elastic tectonic
plate. The probability that one fault remains dormant while the other is active
for a time Dt following the previous activity shift is proportional to the
inverse of Dt to the power 1+x, a result that is robust in the presence of
annealed noise and strength weakening. A mean field theory accounts for the
observed dependence of the persistence exponent x as a function of
heterogeneity and distance between faults. These results continue to hold if
the number of competing faults is increased. This is related to the persistence
phenomenon discovered in a large variety of systems, which specifies how long a
relaxing dynamical system remains in a neighborhood of its initial
configuration. Our persistence exponent is found to vary as a function of
heterogeneity and distance between faults, thus defining a novel universality
class.Comment: 4 pages, 3 figures, Revte
Quasiparticle transport and localization in high-T_c superconductors
We present a theory of the effects of impurity scattering in d_{x^2-y^2}
superconductors and their quantum disordered counterparts, based on a
non-linear sigma model formulation. We show the existence, in a
quasi-two-dimensional system, of a novel spin-metal phase with a non-zero spin
diffusion constant at zero temperature. With decreasing inter-layer coupling,
the system undergoes a quantum phase transition (in a new universality class)
to a localized spin-insulator. Experimental implications for spin and thermal
transport in the high-temperature superconductors are discussed.Comment: 4 pages, 1 figur
Chiral Surface States in the Bulk Quantum Hall Effect
In layered samples which exhibit a bulk quantum Hall effect (QHE), a
two-dimensional (2d) surface ``sheath" of gapless excitations is expected.
These excitations comprise a novel 2d chiral quantum liquid which should
dominate the low temperature transport along the field (z-axis). For the
integer QHE, we show that localization effects are completely absent in the
``sheath", giving a metallic z-axis conductivity. For fractional filling , the ``sheath" is a 2d non-Fermi liquid, with incoherent z-axis transport
and . Experimental implications for the Bechgaard salts
are discussed.Comment: 4 pages, RevTeX 3.0, with two encapsulated postscript figures, which
can be automatically included in-text if desired. The complete postscript
file is available on the WWW at http://www.itp.ucsb.edu/~balents/sheath.p
- …