The structure of the dimeric kinesin heavy chain from Rattus norvegicus has been solved using X-ray crystallography. The resolution of the data extends to 3.1 Å. There is almost no change in the structure of the motor domain compared to the monomeric form. Interestingly the dimer shows an unexpected symmetry. It has a symmetry axis almost parallel to the coiled-coil formed by the two C-terminal alpha-helices alpha-7. The symmetry is a rotation of almost 120° and not the expected 180°. The orientation of the two heads makes it unlikely that both can bind simultaneously to the microtubule lattice.

The colour code used in the figure above corresponds to the different functional parts of the molecule: nucleotide binding regions, microtubule binding region and in dark and light red the neck helices alpha7. Coloured in cyan are the central beta-sheets and in magenta the attached helices. The latter two elements are coloured with different shades of brightness to make the two heads easier to distinguish. Apparently there is no interaction between the two heads except for the coiled coil helices. The dotted line between L8b of head A and L10 of head B shows the point of closest approximation, but no interaction could be determined.

Contributed by Stefan Sack & Eckhard Mandelkow

Reference

F. Kozielski, S. Sack, A. Marx, M. Thormählen, E. Schönbrunn, V. Biou, A. Thompson, E.-M. Mandelkow, E. Mandelkow (1997) The X-ray structure of dimeric kinesin and implications for microtubule-dependent motility. Cell 91:985-994.

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Created 26 August 1998
Modified 21 February 2000 21:30 GMT