The second LIM domain of Lhx9: Lhx9 belongs to the LHX protein family, which features two tandem N-terminal LIM domains and a C-terminal DNA binding homeodomain. Members of LHX family are found in the nucleus and act as transcription factors or cofactors. LHX proteins are critical for the development of specialized cells in multiple tissue types, including the nervous system, skeletal muscle, the heart, the kidneys, and endocrine organs, such as the pituitary gland and the pancreas. Lhx9 is highly homologous to Lhx2. It is expressed in several regions of the developing mouse brain, the spinal cord, the pancreas, in limb mesenchyme, and in the urogenital region. Lhx9 plays critical roles in gonad development. Homozygous mice lacking functional Lhx9 alleles exhibit numerous urogenital defects, such as gonadal agenesis, infertility, and undetectable levels of testosterone and estradiol coupled with high FSH levels. Lhx9 null mice have reduced levels of the Sf1 nuclear receptor that is required for gonadogenesis, and recent studies have shown that Lhx9 is able to activate the Sf1/FtzF1 gene. Lhx9 null mice are phenotypically female, even those that are genotypically male. As in other LIM domains, this domain family is 50-60 amino acids in size and shares two characteristic zinc finger motifs. The two zinc fingers contain eight conserved residues, mostly cysteines and histidines, which coordinately bond to two zinc atoms. LIM domains function as adaptors or scaffolds to support the assembly of multimeric protein.
Comment:The two zinc fingers contain eight conserved residues, mostly cysteines and histidines, which coordinately bond to two zinc atoms. The Zn binding residues of LIM domain are highly conserved.
Jiyao W et al.(2023). "The conserved domain database in 2023.",