Interactions between LIM domains and the LIM domain-binding protein Ldb1

J Biol Chem. 1998 Feb 20;273(8):4712-7. doi: 10.1074/jbc.273.8.4712.


LIM domains mediate protein-protein interactions and, within LIM-homeodomain proteins, act as negative regulators of the transcriptional activation function of the protein. The recently described protein Ldb1 (also known as NLI; LIM domain-binding protein) binds LIM domains in vitro and synergizes with the LIM-homeodomain protein Xlim-1 in frog embryo microinjection experiments. In this study we localized the transcriptional activation domain of Xlim-1 to its carboxyl-terminal region, and characterized the interactions of the amino-terminally located LIM domains with Ldb1. Ldb1 binds LIM domains through its carboxyl-terminal region, and can form homodimers via its amino-terminal region. Optimal binding to Ldb1 required tandem LIM domains, while single domains could bind at lower but clearly measurable efficiency. In animal explant experiments, synergism of Ldb1 with Xlim-1 in the activation of downstream genes required both the region containing the dimerization domain of Ldb1 and the region containing the LIM-binding domain. The role of Ldb1 may be to recruit other transcriptional activators depending on the promoter context and LIM-homeodomain partner involved.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA-Binding Proteins / metabolism*
  • Dimerization
  • Homeodomain Proteins / metabolism*
  • LIM-Homeodomain Proteins
  • Protein Binding
  • Recombinant Proteins / metabolism
  • Transcription Factors
  • Transcriptional Activation
  • Xenopus
  • Xenopus Proteins*


  • DNA-Binding Proteins
  • Homeodomain Proteins
  • LIM-Homeodomain Proteins
  • Lhx1 protein, Xenopus
  • Recombinant Proteins
  • Transcription Factors
  • XLdb1 protein, Xenopus
  • Xenopus Proteins