It is shown that the C. elegans Pax-6 locus encodes two protein isoforms. One contains a Paired DNA binding domain as well as a homeodomain; the other consists only of the carboxy-terminal portion of the locus encoding the homeodomain. These two isoforms are expressed in a variety of postembryonic cell lineages. In one set of lineages, nuclear localization of a homeodomain-only form (MAB-18 isoform) appears to be under temporal and spatial control. Nuclear localization of MAlt-18 is correlated with the genetic requirement for mab-18 and with activation of a reporter gene driven by a mab-18 promoter. Reporter gene expression is dependent on mab-18 gene activity. It is hypothesized that a positive feedback loop is activated by regulated nuclear entry.
Bibliographical noteFunding Information:
We thank members of the Emmons laboratory for their comments on the manuscript. This work was supported by grants from the NIH (GM39353) to S.W.E., the American Cancer Society (DB-149) to D.G., and the NIH (GM54657) to A.C. H.B.F. was a recipient of a Brazilian Research Council (CNPq) Postdoctoral Fellowship. D.G. is the recipient of a Junior Faculty Research Award of the American Cancer Society (JFRA-630). A.C. is an Alfred P. Sloan Research Fellow. S.W.E. is the Siegfried Ullmann Professor of Molecular Genetics.
Copyright 2007 Elsevier B.V., All rights reserved.
- Caenorhabditis elegans
- Homeodomain protein