A possible mechanism for partitioning between homo- and heterodimerization of the yeast homeodomain proteins MATa1 and MATα2

Authors

  • C.-Y. Ho,

    1. present address : Biology Department, University of California at Santa Cruz, 412 Sinsheimer, Santa Cruz, CA 95064, USA.
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  • M. Smith,

    1. Department of Biochemistry and Molecular Biology, Biotechnology Laboratory, and Protein Engineering Network of Centres of Excellence, University of British Columbia, Vancouver, Canada;
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  • M.E. Houston Jr,

    1. Department of Biochemistry, and Protein Engineering Network of Centres of Excellence, University of Alberta, Edmonton, Canada; present addresses: Cytovax Biotechnologies Inc., Suite 308, 8925, 51 Ave, Edmonton, Alberta, Canada T6E 4S5;
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  • J.G. Adamson,

    1. Hemosol nc., 115 Skyway Ave, Etobicoke, Ontario, Canada M9W 4Z4;
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  • R.S. Hodges

    1. Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, 4200 East 9th Ave, Box B-121, Denver, CO, 80262, USA.
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  • To cite this article:

    Houston, M. E. Jr, Ho, C.-Y., Adamson, J. G., Hodges, R. S. & Smith, M. A possible mechanism for partitioning between homo- and heterodimerization of the yeast homeodomain proteins MATa1 and MATα2.

    J. Peptide Res., 2002, 59, 00−00.

    M. E. Houston Jr and C.-Y. Ho contributed equally to this work.

Robert S. Hodges
Department of Biochemistry and Molecular Genetics,
University of Colorado Health Sciences Center,
Campus Box B-121,
4200 East 9th Avenue
Denver,
CO 80262,
USA
Tel.: 303 315 8837
Fax: 303 315 1153
E-mail: robert.hodges@uchsc.edu

Abstract

Abstract: The yeast Saccharomyces cerevisiae has three cell types distinguished by the proteins encoded in their mating-type (MAT) loci: the a and α haploids, which express the DNA-binding proteins a1, and α1 and α2, respectively, and the a/α diploid which expresses both a1 and α2 proteins. In a/α cells, a1−α2 heterodimers repress haploid-specific genes and MATα1, whereas α2 homodimers repress a-specific genes, indicating dual regulatory functions for α2 in mating-type control. We previously demonstrated that the two leucine zipper-like coiled-coil motifs, called α2A and α2B, in the α2 N-terminal domain are important to a1−α2 heterodimerization. A unique feature of α2B is the occurrence of three atypical amino acid residues at a positions within the hydrophobic core. We have conducted mutational analyses of α2B peptides and the full-length protein. Our data suggest that these residues may play a critical role in partitioning of the α2 protein between heterodimerization with a1 and homodimerization with itself.

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