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Science 333 (6046): 1103-1104

Copyright © 2011 by the American Association for the Advancement of Science

A Window on the Sophistication of Plants

Richard A. Jorgensen

Flowering plants possess the remarkable capacity to selectively move large, functional proteins and RNA molecules between cells through regulated channels called plasmodesmata (1). For example, within a meristem (a group of stem cells) plants can steer macromolecular traffic in particular directions along these "highways" to orchestrate stem cell division and the development of specialized tissues. How they control this cell-to-cell traffic, however, has been a question of major importance. On page 1141 of this issue, Xu et al. (2) reach a major milestone in the quest for an answer. They show that selective trafficking of a functional protein, the maize transcription factor KNOTTED1 (KN1), requires KN1 to unfold and then be refolded in the destination cell by a group of proteins known as the chaperonin complex.

Langebio, Cinvestav Irapuato, Guanajuato 36821 Mexico.

E-mail: rajorgensen{at}

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