The second LIM domain of LMO4 (LIM domain only protein 4)
The second LIM domain of LMO4 (LIM domain only protein 4): LMO4 is a nuclear protein that plays important roles in transcriptional regulation and development. LMO4 is involved in various functions in tumorigenesis and cellular differentiation. LMO4 proteins regulate gene expression by interacting with a wide variety of transcription factors and cofactors to form large transcription complexes. It can interact with Smad proteins, and associate with the promoter of the PAI-1 (plasminogen activator inhibitor-1) gene in a TGFbeta (transforming growth factor beta)-dependent manner. LMO4 can also form a complex with transcription regulator CREB (cAMP response element-binding protein) and interact with CLIM1 and CLIM2. In breast tissue, LMO4 interacts with multiple proteins, including the cofactor CtIP [CtBP (C-terminal binding protein)-interacting protein], the breast and ovarian tumor suppressor BRCA1 (breast-cancer susceptibility gene 1) and the LIM-domain-binding protein LDB1. Functionally, LMO4 is shown to repress BRCA1-mediated transcription activation, thus invoking a potential role for LMO4 as a negative regulator of BRCA1 in sporadic breast cancer. LMO4 also forms complex to both ERa (oestrogen receptor alpha), MTA1 (metastasis tumor antigen 1), and HDACs (histone deacetylases), implying that LMO4 is also a component of the MTA1 corepressor complex. Over-expressed LMO4 represses ERa transactivation functions in an HDAC-dependent manner, and contributes to the process of breast cancer progression by allowing the development of Era-negative phenotypes. All LIM domains are 50-60 amino acids in size and share 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 complexes.
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.",