This entry represents the MI domain (after MA-3 and eIF4G), it is a protein-protein interaction module of ~130 amino acids [ (PUBMED:10958635) (PUBMED:10973054) (PUBMED:15082783) ]. It appears in several translation factors and is found in:
One copy in plant and animal eIF4G 1 and 2 (DAP-5/NAT1/p97)
Two copies in the animal programmed cell death protein 4 (PDCD4) or MA-3 that is induced during programmed cell death and inhibits neoplastic transformation
Four tandem-repeated copies in a group of uncharacterised plant proteins
The MI domain consists of seven alpha-helices, which pack into a globular form. The packing arrangement consists of repeating pairs of antiparallel helices packed one upon the other such that a superhelical axis is generated perpendicular to the alpha-helical axes [ (PUBMED:17060447) ].
The MI domain has also been named MA3 domain.
Family alignment:
There are 8427 MA3 domains in 6622 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing MA3 domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with MA3 domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing MA3 domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Cloning of the TIS gene suppressed by topoisomerase inhibitors.
Gene. 1998; 215: 453-9
Display abstract
We recently cloned the cDNA TIS (topoisomerase inhibitor-suppressed) in RVC lymphoma cells exposed to the topoisomerase inhibitors. To elucidate the suppression mechanism of the TIS mRNA by camptothecin, we characterized the structures of the TIS gene. The gene spanned about 21 kb including 11 exons and was present as a single copy. The putative transcription site was present 192 bp upstream from the ATG codon. The typical TATA sequence and CCAAT promoter element were located at positions -21 and -81, respectively. The unidirectional deletion analysis of the 5'-flanking region revealed that [-132/+160] is the promoter region, which participates in the responsiveness to camptothecin. A Northern blot analysis showed that the TIS was expressed in most mouse tissues; at the highest level in the liver and to less extent in the heart and skeletal muscle. The present study showed that the expression of the TIS is suppressed at the transcriptional level by camptothecin. Considering that topoisomerase I is an essential enzyme in mammalian cells, the TIS protein may have an important role in camptothecin toxicity.
A new translational regulator with homology to eukaryotic translation initiation factor 4G.
EMBO J. 1997; 16: 817-25
Display abstract
Translation initiation in eukaryotes is facilitated by the cap structure, m7GpppN (where N is any nucleotide). Eukaryotic translation initiation factor 4F (eIF4F) is a cap binding protein complex that consists of three subunits: eIF4A, eIF4E and eIF4G. eIF4G interacts directly with eIF4E and eIF4A. The binding site of eIF4E resides in the N-terminal third of eIF4G, while eIF4A and eIF3 binding sites are present in the C-terminal two-thirds. Here, we describe a new eukaryotic translational regulator (hereafter called p97) which exhibits 28% identity to the C-terminal two-thirds of eIF4G. p97 mRNA has no initiator AUG and translation starts exclusively at a GUG codon. The GUG-initiated open reading frame (907 amino acids) has no canonical eIF4E binding site. p97 binds to eIF4A and eIF3, but not to eIF4E. Transient transfection experiments show that p97 suppresses both cap-dependent and independent translation, while eIF4G supports both translation pathways. Furthermore, inducible expression of p97 reduces overall protein synthesis. These results suggest that p97 functions as a general repressor of translation by forming translationally inactive complexes that include eIF4A and eIF3, but exclude eIF4E.
DAP-5, a novel homolog of eukaryotic translation initiation factor 4G isolated as a putative modulator of gamma interferon-induced programmed cell death.
Mol Cell Biol. 1997; 17: 1615-25
Display abstract
A functional approach to gene cloning was applied to HeLa cells in an attempt to isolate cDNA fragments which convey resistance to gamma interferon (IFN-gamma)-induced programmed cell death. One of the rescued cDNAs, described in this work, was a fragment of a novel gene, named DAP-5. Analysis of a DAP-5 full-length cDNA clone revealed that it codes for a 97-kDa protein that is highly homologous to eukaryotic translation initiation factor 4G (eIF4G, also known as p220). According to its deduced amino acid sequence, this novel protein lacks the N-terminal region of eIF4G responsible for association with the cap binding protein eIF4E. The N-terminal part of DAP-5 has 39% identity and 63% similarity to the central region of mammalian p220. Its C-terminal part is less homologous to the corresponding region of p220, suggesting that it may possess unique functional properties. The rescued DAP-5 cDNA fragment which conveyed resistance to IFN-gamma-induced cell death was expressed from the vector in the sense orientation. Intriguingly, it comprised part of the coding region which corresponds to the less conserved C-terminal part of DAP-5 and directed the synthesis of a 28-kDa miniprotein. The miniprotein exerted a dual effect on HeLa cells. Low levels of expression protected the cells from IFN-gamma-induced programmed cell death, while high levels of expression were not compatible with continuous cell growth. The relevance of DAP-5 protein to possible changes in a cell's translational machinery during programmed cell death and growth arrest is discussed.
cDNA cloning, expression analysis, and chromosomal localization of a gene with high homology to wheat eIF-(iso)4F and mammalian eIF-4G.
Genomics. 1997; 39: 192-7
Display abstract
A novel mammalian gene, Eif4g2, with a high degree of homology to the p82 subunit of the wheat germ eukaryotic translation initiation factor eIF-(iso)4F and mammalian eIF-4G has been isolated. Zoo blot analysis indicates that Eif4g2 is a single-copy gene that is highly conserved among vertebrates. Northern blot analysis shows that Eif4g2 is ubiquitously expressed at high levels in all human and mouse tissues examined. The 3810-nucleotide Eif4g2 cDNA contains a 907-amino-acid open reading frame that codes for a polypeptide with a predicted molecular mass of 102 kDa. The Eif4g2 polypeptide exhibits an overall similarity to wheat p82 of 52%. A 248-amino-acid segment at the amino-terminal end of both peptides exhibits 63% similarity and contains conserved potential RNA binding domains and a phosphorylation site. The Eif4g2 polypeptide contains multiple potential N-linked glycosylation sites as well as protein kinase C and casein kinase II phosphorylation sites. Southern blot analysis of DNA from interspecific backcross mice shows that Eif4g2 is localized to distal mouse chromosome 7 in a region syntenic with human chromosome 11p15.
Isolation of a novel mouse gene MA-3 that is induced upon programmed cell death.
Gene. 1995; 166: 297-301
Display abstract
Typical programmed cell death requires de novo macromolecular synthesis and shares common morphological changes referred to as apoptosis. To elucidate the molecular mechanism of apoptosis, we isolated cDNA clones that are induced in various types of apoptosis by the differential display method. Among such clones, the MA-3 mRNA was induced in all apoptosis-inducible cell lines tested so far, including thymocytes, T cells, B cells and pheochromocytoma. The nucleotide sequence of the MA-3 cDNA predicted an amino acid (aa) sequence of 469 aa, which did not reveal significant similarity to any known proteins and functional aa motifs in databases. The MA-3 mRNA was strongly expressed in the thymus although small amounts of the MA-3 mRNA were ubiquitously expressed in mouse adult tissues. The MA-3 gene was highly conserved during evolution and cross-hybridization bands were found not only in vertebrates but also in Drosophila melanogaster.
