1,402 research outputs found
Mechanisms of Membrane Curvature Generation in Membrane Traffic
During the vesicular trafficking process, cellular membranes undergo dynamic morphological changes, in particular at the vesicle generation and fusion steps. Changes in membrane shape are regulated by small GTPases, coat proteins and other accessory proteins, such as BAR domain-containing proteins. In addition, membrane deformation entails changes in the lipid composition as well as asymmetric distribution of lipids over the two leaflets of the membrane bilayer. Given that P4-ATPases, which catalyze unidirectional flipping of lipid molecules from the exoplasmic to the cytoplasmic leaflets of the bilayer, are crucial for the trafficking of proteins in the secretory and endocytic pathways, changes in the lipid composition are involved in the vesicular trafficking process. Membrane remodeling is under complex regulation that involves the composition and distribution of lipids as well as assembly of proteins
A simply connected surface of general type with p_g=0 and K^2=3
Motivated by a recent result of Y. Lee and the second author[7], we construct
a simply connected minimal complex surface of general type with p_g=0 and K^2=3
using a rational blow-down surgery and Q-Gorenstein smoothing theory. In a
similar fashion, we also construct a new simply connected symplectic 4-manifold
with b_2^+=1 and K^2=4.Comment: 17 pages, 10 figures, a section regarding a symplectic 4-manifold
with K^2=4 is adde
Membrane Fuzzy Sphere Dynamics in Plane-Wave Matrix Model
In plane-wave matrix model, the membrane fuzzy sphere extended in the SO(3)
symmetric space is allowed to have periodic motion on a sub-plane in the SO(6)
symmetric space. We consider a background configuration composed of two such
fuzzy spheres moving on the same sub-plane and the one-loop quantum corrections
to it. The one-loop effective action describing the fuzzy sphere interaction is
computed up to the sub-leading order in the limit that the mean distance
between two fuzzy spheres is very large. We show that the leading order
interaction is of the 1/r^7 type and thus the membrane fuzzy spheres
interpreted as giant gravitons really behave as gravitons.Comment: 28 pages, LaTeX2e, 1 figure, 1 tabl
Thermodynamics of Fuzzy Spheres in PP-wave Matrix Model
We discuss thermodynamics of fuzzy spheres in a matrix model on a pp-wave
background. The exact free energy in the fuzzy sphere vacuum is computed in the
\mu -> \infty limit for an arbitrary matrix size N. The trivial vacuum
dominates the fuzzy sphere vacuum at low temperature while the fuzzy sphere
vacuum is more stable than the trivial vacuum at sufficiently high temperature.
Our result supports that the fluctuations around the trivial vacuum would
condense to form an irreducible fuzzy sphere above a certain temperature.Comment: 18 pages, 4 figures, LaTeX2
Thermodynamic Behavior of Fuzzy Membranes in PP-Wave Matrix Model
We discuss a two-body interaction of membrane fuzzy spheres in a pp-wave
matrix model at finite temperature by considering a fuzzy sphere rotates with a
constant radius r around the other one sitting at the origin in the SO(6)
symmetric space. This system of two fuzzy spheres is supersymmetric at zero
temperature and there is no interaction between them. Once the system is
coupled to the heat bath, supersymmetries are completely broken and non-trivial
interaction appears. We numerically show that the potential between fuzzy
spheres is attractive and so the rotating fuzzy sphere tends to fall into the
origin. The analytic formula of the free energy is also evaluated in the large
N limit. It is well approximated by a polylog-function.Comment: 13 pages, 4 figures, LaTe
ATPase reaction cycle of P4-ATPases affects their transport from the endoplasmic reticulum
P4‐ATPases belonging to the P‐type ATPase superfamily mediate active transport of phospholipids across cellular membranes. Most P4‐ATPases, except ATP9A and ATP9B proteins, form heteromeric complexes with CDC50 proteins, which are required for transport of P4‐ATPases from the endoplasmic reticulum (ER) to their final destinations. P‐type ATPases form autophosphorylated intermediates during the ATPase reaction cycle. However, the association of the catalytic cycle of P4‐ATPases with their transport from the ER and their cellular localization has not been studied. Here, we show that transport of ATP9 and ATP11 proteins as well as that of ATP10A from the ER depends on the ATPase catalytic cycle, suggesting that conformational changes in P4‐ATPases during the catalytic cycle are crucial for their transport from the ER
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