EELM2, the extended EGL-27 and MTA1 homology domain, occurs in proteins from apicomplexan parasites. Part of the EELM2 domain is homologous to the ELM2 domain, but is 'extended' in that its boundaries (the region of conservation) are longer than in the ELM2 domain. Currently (as of 2012), little is known about the function of this domain. However, some proteins that contain an EELM2 domain also contain a PHD finger domain, which is thought to be involved in chromatin remodelling. This suggests an associated role for the EELM2 domain [].
The ELM2 (Egl-27 and MTA1 homology 2) domain is a small domain of unknown function. It is found in the MTA1 protein that is part of the NuRD complex []. The domain is usually found to the N terminus of a myb-like DNA binding domain and a GATA binding domain. ELM2, in some instances, is also found associated with the ARID DNA binding domain . This suggests that ELM2 may also be involved in DNA binding, or perhaps is a protein-protein interaction domain.
The R1 domain is found in the MTA1 protein and its homologues. The domain is composed of 4 alpha helices. It has been shown to bind to the RBBP4 protein []. The MTA proteins contain a second partial copy of this domain called R2. The R2 domain is matched by this model for some proteins.
MTA (metastasis-associated) proteins, including MTA1-3, are transcriptional co-repressors that function in histone deacetylation and are involved in the NuRD complex. Nevertheless, MTA1 and MTA2 have been shown to deacetylate non-histone proteins, such as p53. The expression of MTA proteins have been linked to human cancers [].Mesoderm induction early response proteins (MIER1-3) are ELM2-SANT domain-containing proteins. MIER1 functions as a transcriptional repressor through its ability to recruit HDAC1/2 activity[]. The function of MIER2 and MIER3 is not clear [].
Metastasis-associated protein MTA2 is a component of the nucleosome-remodeling and histone-deacetylase multiprotein complex (NuRD) []. It is a member of the MTA family.MTA (metastasis-associated) family members, including MTA1-3, are transcriptional co-repressors that function in histone deacetylation and are involved in the NuRD complex. Nevertheless, MTA1 and MTA2 have been shown to deacetylate non-histone proteins, such as p53. The expression of the MTA family members have been linked to human cancers [].
Hypermethylated in cancer 1 (HIC1) is a transcriptional repressor that modulates P53-dependent and E2F1-dependent cell growth control and is epigenetically inactivated in various human cancers []. It recognises and binds to the consensus sequence '5-[CG]NG[CG]GGGCA[CA]CC-3' []. It is a direct transcriptional repressor of ephrin-A1 and CXCR7, which are implicated in the pathogenesis of different cancers [, ]. HIC1 is also involved in down-regulation of SIRT1 and thereby is involved in regulation of p53/TP53-dependent apoptotic DNA-damage responses []. HIC1 interacts with several different corepressors such as CTBP1, CTBP2 and MTA1 (a subunit of the NuRD complex) [].
