Molecular Analysis of the Cell Plate Forming Machinery 315
property of this group of proteins, i.e., the ability to form helical structures
regulated by their GTPase activity, is central to their functions. Despite the
high similarity in the structure of various members of the DRP family, it is
apparent that they interact with distinct proteins to perform specific roles
in each of these events. A detailed dissection of various domains of these
proteins and their interaction with specific partners may reveal their pre-
cise function in various cellular processes that involve membrane tubulation,
pinching as well as organelle divisions. Development ofin vitromembrane
vesiculation, tubulation and fusion systems will further aid in dissection of
the details of these mechanisms and the role of various DRPs.
The cell plate is one of a few organelles that have yet to be characterized
using modern proteomic technology. The reason for the lack of proteomic
characterization of the cell plate is mainly due to the technical challenge in
preparing a highly purified cell plate fraction from a plant species with com-
pleted genome sequences, such asArabidopsis.Thistechnicalhurdlemay
disappear soon as the tobacco genome sequencing project progresses. To-
bacco BY-2 cells are easy to synchronize and have been used successfully for
cell plate purification. Proteomic studies on tobacco BY-2 cells will promise
the discovery of many expected as well as many unknown proteins that are
targeted to this essential cytokinetic organelle. Besides the components of the
cell plate itself, other proteins that are involved in the orientation of cell plate,
preprophase band formation and the decision of the cell in which direction to
lay down the cell plate, remain to be determined.
AcknowledgementsThis work was supported by NSF grants to DPSV (IBN-0095112) and
ZH (MCB-0548525 and IOB 0543923).
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