PROSITE documentation PDOC51041

EMI domain profile

The EMI domain, first named after its presence in proteins of the EMILIN family, is a small cysteine-rich module of ~75 amino acids. The EMI domain is most often found at the N-terminus of metazoan extracellular proteins that are forming or are compatible with multimer formation [1]. It is found in association with other domains, such as C1q (see <PDOC00857>), laminin-type EGF-like, collagen-like, FN3 (see <PDOC50853>), WAP (see <PDOC00026>), ZP (see <PDOC00577>) or FAS1 (see <PDOC50213>) [2]. It has been suggested that the EMI domain could be a protein-protein interaction module, as the EMI domain of EMILIN-1 was found to interact with the C1q domain of EMILIN-2 [1].

The EMI domain possesses six highly conserved cysteines residues, which likely form disulfide bonds. Other key features of the EMI domain are the C-C-x-G-[WYFH] pattern, a hydrophobic position just preceding the first cysteine (Cys1) of the domain and a cluster of hydrophobic residues between Cys3 and Cys4. The EMI domain could be made of two sub-domains, the fold of the second one sharing similarities with the C-terminal sub-module characteristic of EGF-like domains [2].

Some proteins known to contain a EMI domain are listed below:

• Vertebrate Emilins, extracellular matrix glycoproteins.
• Vertebrate Multimerins, extracellular matrix glycoproteins.
• Vetebrate Emu proteins. They could interact with several different extracellular matrix components and serve to connect and integrate the function of multiple partner molecules.
• Vertebrate β IG-H3.
• Vertebrate osteoblast-specific factor 2 (OSF-2).
• Mammalian NEU1/NG3 proteins.
• Drosophila midline fasciclin.
• Caenorhabditis elegans ced-1, a transmembrane receptor that mediates cell corpse engulfment.

The profile we developed covers the entire EMI domain.