Cytoskeletal Motor Proteins in Plant Cell Division 187
toskeletal motors are yet to be revealed. While concerted roles of these motors
are required during cell division, their activities are regulated by means
of cell-cycle dependent expression, post-translational modifications, and
turnovers. Additional regulatory mechanisms include activation by cargo-
binding and inhibition by Ca++/calmodulin-binding. Despite many common
phenomena in cell division among eukaryotes, simple recapitulation of func-
tions of animal kinesins for plant ones in the same subfamily will certainly be
an inappropriate practice. Characterizing functions of individual cytoskele-
tal motors in cell division would be the key for us to appreciate molecular
mechanisms that regulate plant mitosis, meiosis, and cytokinesis.
AcknowledgementsOur studies of plant kinesins have been generously supported by grants
from the US Department of Agriculture Cooperative State Research, Education and Exten-
sion Service and the US Department of Energy Energy Biosciences programs. We wish to
thank Drs. Mary Preuss and Fengli Guo for contributing pictures shown in Figs. 2 and 6.
References
Ambrose JC, Li W, Marcus A, Ma H, Cyr R (2005) A minus-end-directed kinesin with
plus-end tracking protein activity is involved in spindle morphogenesis. Mol Biol Cell
16:1584–1592
Asada T, Kuriyama R, Shibaoka H (1997) TKRP125, a kinesin-related protein involved
in the centrosome-independent organization of the cytokinetic apparatus in tobacco
BY-2 cells. J Cell Sci 110:179–189
Asada T, Shibaoka H (1994) Isolation of polypeptides with microtubule-translocating ac-
tivity from phragmoplasts of tobacco BY-2 cells. J Cell Sci 107:2249–57
Asada T, Sonobe S, Shibaoka H (1991) Microtubule translocation in the cytokinetic appa-
ratus of cultured tobacco cells. Nature 350:238–241
Austin JR, Segui-Simarro JM, Staehelin LA (2005) Quantitative analysis of changes in
spatial distribution and plus-end geometry of microtubules involved in plant-cell cy-
tokinesis. J Cell Sci 118:3895–3903
Barroso C, Chan J, Allan V, Doonan J, Hussey P, Lloyd C (2000) Two kinesin-related pro-
teins associated with the cold-stable cytoskeleton of carrot cells: characterization of
a novel kinesin, DcKRP120-2. Plant J 24:859–868
Bednarek SY, Falbel TG (2002) Membrane trafficking during plant cytokinesis. Traffic
3:621–629
Berg J, Powell B, Cheney R (2001) A millennial myosin census. Mol Biol Cell 12:780–794
Bisgrove S, Hable W, Kropf D (2004) +TIPs and microtubule regulation. The beginning of
the plus end in plants. Plant Physiol 136:3855–3863
Blangy A, Lane HA, Dherin P, Harper M, Kress M, Nigg EA (1995) Phosphorylation by
p34(cdc2)regulates spindle association of human Eg5, a kinesin-related motor essential
for bipolar spindle formation in vivo. Cell 83:1159–1169
Bogre L, Calderini O, Binarova P, Mattauch M, Till S, Kiegerl S, Jonak C, Pollaschek C,
Barker P, Huskisson NS et al. (1999) A MAP kinase is activated late in plant mitosis
and becomes localized to the plane of cell division. Plant Cell 11:101–113
Bowser J, Reddy ASN (1997) Localization of a kinesin-like calmodulin-binding protein in
dividing cells of Arabidopsis and tobacco. Plant J 12:1429–1437