Biophysical studies of membrane proteins/peptides. Interaction with ...

INTERACTION OF HELIX-0 OF THE N-BAR DOMAIN
WITH LIPID BILAYERS
V
INTERACTION OF HELIX-0 OF
THE N-BAR DOMAIN WITH
LIPID MEMBRANES
1. Introduction
Endocytosis is a crucial phenomenon in several cellular processes, such as
receptor recycling and degradation, delivery of membrane-bound and soluble cargo to
intracellular organelles, and nutrient uptake. Clathrin-mediated endocytosis is likely to
be the best characterized of all endocytic pathways, and is responsible for recycling of
proteins from the plasma membrane. It is also important in the recycling of synaptic
vesicles. A complex assemble of clathrin and several other proteins drives invagination
of the plasma membrane and ultimately fission (Dawson et al., 2006). Therefore,
clathrin mediated endocytosis can be separated in two steps. In the first step, the
membrane must bend inwards to create a vesicular structure. Following this, the vesicle
is actively pinched off from the membrane. The last step is known to be carried out by a
protein called dynamin that polymerizes upon membrane binding and arranges into
coiled coats around the neck of the nascent vesicles, twisting (through an unknown
mechanism) in response to GTP hydrolysis, leading to fission of the vesicle (McMahon
and Gallop, 2005).
In recent years, studies have been unravelling the complex network of proteins
involved in clathrin mediated endocytosis. In the end of the last decade, De Camilli and
co-workers (Takei et al, 1998; Takei et al, 1999) observed that a protein called
amphiphysin, known to interact with dynamin during endocytosis, bounds to spherical
liposomes and induces formation of tubules both in the presence and absence of
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