The study published in the Proceedings of the National Academy of Sciences (PNAS) gives the first clear details of how the binding sites of CaMKII act to align actin filaments
into long, rigid bundles.
A collaborative study led by MBI doctoral student Chen Tianchi and Professor Benoit Ladoux of the Mechanobiology Institute (MBI) at the National University of Singapore, has uncovered that the direction in which actin filaments
flow within the cell allows it to sense the physical curvature of its surroundings, and this directional flow is the key switch that determines which method of migration is selected.
Ordinarily, as filaments of the myosin protein absorb energy, they bind to filaments of the protein actin and bend back upon themselves, pulling on the actin filaments
and contracting the muscle.
FLNC belongs to the filamin superfamily and cross-links actin filaments
to form a network, anchoring membrane protein to the cytoskeleton.
Previous studies have reported that CAPZB is an essential element of the actin cytoskeleton whereby it binds to the barbed ends of actin filaments
and regulates their polymerization .
The transformation of the chemical energy released during the conformational change (stroke) into mechanical energy is brought about by the binding of CBs to actin filaments
, which couples the stroking to shortening through sliding actin filaments
Cofilin-1 (CFL1) is an actinbinding protein that is essential for the depolymerization of actin filaments
Myosin II is an adenosine triphosphate (ATP)dependent protein that generates force and movement along the actin filaments
. The "swinging lever-arm" hypothesis of muscle contraction purposes that nucleotide-dependent small movements of the ATPase catalytic site are amplified by the rotation of the myosin molecule "neck", and it is accepted as the general mechanism by which the sarcomere shortening occurs (Shiroguchi et al., 2011).
To visualize actin filaments
, after the secondary antibody incubation, the zygotes were treated with a 200-fold dilution of rhodamine phalloidin (R415; Molecular Probes) by DW for 2 h at room temperature and then rinsed in rinse solution three times.
In the region around the nucleus (5< x <10 pm and 22< x < 30 [micro]m), there exists actin filaments
network which plays a key role in cellular mechanical stability, and therefore we observe increase of elastic modulus in this area.
Considering that actin filaments
are assembled by noncovalent interactions, this provides a higher potential of exchange between the monomeric and the filamentous states.
Maruyama, "Human T cell L-plastin bundles actin filaments
in a calcium dependent manner," Journal of Biochemistry, vol.