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Cortexillin

A 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 et al, ), 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, 1999).

References:-

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.

Faix, 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.

Weber, 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.

 
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