InterPro domain: IPR003891

This entry represents the MI domain (after MA-3 and eIF4G), it is a protein-protein interaction module of ~130 amino acids [ 1 , 2 , 3 ]. 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 [ 4 ].

The MI domain has also been named MA3 domain.

1. Eukaryote-specific domains in translation initiation factors: implications for translation regulation and evolution of the translation system. Genome Res. 10, 1172-84
2. Novel eIF4G domain homologues linking mRNA translation with nonsense-mediated mRNA decay. Trends Biochem. Sci. 25, 423-6
3. A novel function of the MA-3 domains in transformation and translation suppressor Pdcd4 is essential for its binding to eukaryotic translation initiation factor 4A. Mol. Cell. Biol. 24, 3894-906
4. Structural basis for inhibition of translation by the tumor suppressor Pdcd4. Mol. Cell. Biol. 27, 147-56