coiled-coil protein first identified in Dictyostelium
discoideum that forms a homodimer. The parallel dimer is composed
of four domains from N- to C-terminus, first the actin-binding domain consisting
of CH domains, the second coiled-coil domain dimerises the molecule (Burkhard
), a third
hinge domain followed by a coiled domain in the C- terminal. Cortexillins
are present in Dictyostelium as two isoforms, cortexillin I and
cortexillin II and similar proteins have been inferred from cDNA data in Physarum
polycephalum. Actin binding is calcium independent and the bundles
that form in its presence are preferentially anti-parallel which is surprising
given the parallel arrangement of the homodimer confirmed by low angle rotary
electron microscopy (Faix,
Burkhard P. Kammerer
RA. Steinmetz MO. Bourenkov GP. Aebi U. "The coiled-coil trigger site of
the rod domain of cortexillin I unveils a distinct network of interhelical and
intrahelical salt bridges." Structure. 8(3), 223-230
Faix, J.M. (1999).
"Cortexillins" in Guidebook to the Cytoskeletal and Motor Proteins,
2nd ed. Eds. Kreis, T. & Vale, R.
J., M. Steinmetz, et al. (1996). “Cortexillins, major determinants of cell
shape and size, are actin bundling proteins with a parallel coiled-coil tail.”
Cell 86, 631-642.
I., Neujahr, R., Du, A., Kohler, J., Faix, J. & Gerisch, G. (2000).
"Two step positioning of a cleavage furrow by cortexillin and myosin
II." Curr.Biol. 10, 501-506.