Chalfie's Abstract

Science 261: 1324-8 (1993)[93369588]

Cooperative interactions between the Caenorhabditis elegans homeoproteins UNC-86 and MEC-3.

D. Xue, Y. Tu & M. Chalfie

Department of Biological Sciences, Columbia University, New York, NY 10027.

The POU-type homeodomain protein UNC-86 and the LIM-type homeodomain protein MEC-3, which specify neuronal cell fate in the nematode Caenorhabditis elegans, bind cooperatively as a heterodimer to the mec-3 promoter. Heterodimer formation increases DNA binding stability and, therefore, increases DNA binding specificity. The in vivo significance of this heterodimer formation in neuronal differentiation is suggested by (i) a loss-of-function mec-3 mutation whose product in vitro binds DNA well but forms heterodimers with UNC-86 poorly and (ii) a mec-3 mutation with wild-type function whose product binds DNA poorly but forms heterodimers well.

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