Cell-to-Cell Movement of Homeodomain Transcription Factors: Yesterday, Today and Tomorrow
Cell-to-cell communication is pivotal for the coordinated behavior of cells, and thus the orchestrated development of any multicellular organism. One special means of communication is the direct transfer of macromolecules, including transcription factors, between plant cells through plasmodesmata. KNOTTED1 (KN1), a maize homeodomain transcription factor, was the first plant protein identified to traffic between cells. KN1 belongs to a family of essential proteins functioning during stem cell maintenance in the shoot apical meristem. Here we recall the history of the remarkable finding of KN1 trafficking, and summarize our current understanding of its mechanism, regulation and potential significance. We also touch upon some of the important questions remaining for future exploration.
KeywordsShoot Apical Meristem Fluorescence Recovery After Photobleaching Homeodomain Protein Size Exclusion Limit KNOX Protein
Thanks to Kate Creasey for critical reading. X. M. X. is a LSRF Fellow of the Life Sciences Research Foundation and a Chapman Fellow of the Chapman Foundation. Relevant research in the authors’ laboratory is supported by the National Science Foundation (award 1027003).
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