[Faculty] Fwd: [CSRC-SDSU COLLOQUIUM]: The role of membrane tension in clathrin-mediated endocytosis

[Jose Castillo]

---------- Forwarded message ----------
From: "Angel Armando Boada Velazco" <angelboada2 at gmail.com>
Date: Apr 20, 2016 4:13 PM
Subject: [CSRC-SDSU COLLOQUIUM]: The role of membrane tension in
clathrin-mediated endocytosis
To: <csca at roswell.sdsu.edu>
Cc:

*DATE*:  Friday, April 22nd, 2016

*TITLE*:   The role of membrane tension in clathrin-mediated endocytosis

*TIME*:  3:30 PM

*LOCATION*:  GMCS 214

*SPEAKER*:  Dr. Padmini Rangamani. Assistant Professor in Mechanical
Engineering, University of California, San Diego.

*ABSTRACT*:  In clathrin-mediated endocytosis (CME), clathrin and various
adaptor proteins coat a patch of the plasma membrane, which is reshaped to
form a budded vesicle. Experimental studies have demonstrated that elevated
membrane tension can inhibit bud formation by a clathrin coat. I will first
discuss recent results that show that membrane tension can be heterogeneous
along the surface of the membrane and depend on protein concentration. Then
I will discuss the mechanics of membrane budding across a range of membrane
tensions by simulating clathrin coats that either grow in area or
progressively induce greater curvature. At low membrane tension,
progressively increasing the area of a curvature-generating coat causes the
membrane to smoothly evolve from a flat to budded morphology, whereas the
membrane remains essentially flat at high membrane tensions. Interestingly,
at physiologically relevant, intermediate membrane tensions, the shape
evolution of the membrane undergoes a ‘’snapthrough instability'' in which
increasing coat area causes the membrane to ``snap'' from an open, U-shaped
bud to a closed, Ω-shaped bud. This instability is accompanied by a large
energy barrier, which could cause a developing endocytic pit to stall if
the binding energy of additional coat is insufficient to overcome this
barrier. Similar results were found for a coat of constant area in which
the spontaneous curvature progressively increases. Additionally, we found
that a pulling force on the bud, simulating a force from actin
polymerization, is sufficient to drive a transition from an open to closed
bud, overcoming the energy barrier opposing this transition.

*HOST*: Dr. Jose Castillo

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SDSU Computational Science Research Center
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