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Cloning and functional characterization of chicken p160 coactivator family members
1Laboratory of Environmental Biochemistry, School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, 565-0871, Osaka, Japan.
Abstract:
The factors SRC-1, TIF2 and ACTR were identified as interacting with nuclear receptors in a highly ligand-dependent manner. Because the molecular mass of each of these factors is approximately 160 kDa, they are collectively termed p160 coactivators. So far, p160 coactivators have been cloned from human, mouse and Xenopus. We report here the cloning of the chicken homologues of p160 coactivator members. As in human and mouse, chicken has three p160 coactivators. Each gene encodes an approximately 160 kDa protein which exhibits 70-80% amino acid sequence identity to human and mouse p160 coactivators. Chicken p160 coactivators also have the property of interacting with several liganded nuclear receptors. Moreover, we describe an imperfect LXXLL sequence, termed NR box 4, which is located downstream of NR box 3 and conserved between evolutionarily diverse species. The loss of NR box 4 results in a decrease of interaction with the nuclear receptor, which indicates that NR box 4 is required for efficient interaction.
Insights
Researchers cloned chicken p160 coactivators, revealing conserved interactions with nuclear receptors. A novel NR box 4 sequence is crucial for efficient receptor binding, highlighting its evolutionary importance.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- p160 coactivators (SRC-1, TIF2, ACTR) interact with nuclear receptors in a ligand-dependent manner.
- These coactivators, approximately 160 kDa, have been identified in humans, mice, and Xenopus.
Purpose of the Study:
- To clone and characterize chicken homologues of p160 coactivator members.
- To investigate the interaction properties of chicken p160 coactivators with nuclear receptors.
- To identify and analyze novel conserved sequences within p160 coactivators.
Main Methods:
- Gene cloning of chicken p160 coactivator members.
- Amino acid sequence analysis and comparison with human and mouse homologues.
- Functional assays to assess interaction with liganded nuclear receptors.
Main Results:
- Three chicken p160 coactivator genes were cloned, encoding ~160 kDa proteins with 70-80% sequence identity to mammalian counterparts.
- Chicken p160 coactivators demonstrated interaction with various liganded nuclear receptors.
- A conserved, imperfect LXXLL motif, termed NR box 4, was identified downstream of NR box 3.
- Disruption of NR box 4 significantly reduced nuclear receptor interaction, indicating its functional importance.
Conclusions:
- Chicken possesses three p160 coactivators homologous to those in mammals, underscoring conserved coactivator function across species.
- NR box 4 is a functionally significant motif required for efficient nuclear receptor binding, conserved across diverse species.