PerspectiveProtein Domains

Dual Functions of the KNOTTED1 Homeodomain: Sequence-Specific DNA Binding and Regulation of Cell-to-Cell Transport

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Sci. Signal.  10 Jun 2008:
Vol. 1, Issue 23, pp. pe28
DOI: 10.1126/scisignal.123pe28

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Homeodomain proteins are well-characterized developmental regulators that control expression of target genes through sequence-specific DNA binding. The homeodomain forms a trihelical structure, with the third helix conferring specific interactions with the DNA major groove. A specific class of plant homeodomain proteins, called KNOX [KNOTTED1 (KN1)-like homeobox], also has the ability to signal between cells by directly trafficking through intercellular channels called plasmodesmata. Trafficking is mediated by a signal that is also contained within the homeodomain. Movement protein binding protein 2C was identified as a protein that interacts with the KN1 homeodomain and regulates the cell-to-cell trafficking of KN1 by sequestering the protein on microtubules. Therefore, KN1 has multiple potential cellular addresses, each of which is conferred by its homeodomain.

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