Tomoregulin (TR)

The deduced 368-amino acid TRa protein contains 2 follistatin-like domains and a conserved EGF-like domain. It also has a predicted N-terminal signal peptide, a transmembrane domain, a cytosolic tail G protein-activating motif, and potential sites for N-linked glycosylation and glycosaminoglycan attachment. Unlike other EGF/NRG family members, TRa has a histidine replacing a conserved arginine essential for EGF receptor recognition. The TRb and TRc proteins contain 418 and 379 amino acids, respectively, and differ from one another and TRa in the cytoplasmic domain. Northern blot analysis detected expression of approximately 2.2- and 3.1-kb TR transcripts predominantly in brain. The 374-amino acid TMEFF2 protein shares approximately 36% and 99% sequence identity with TMEFF1 and mouse Tmeff2, respectively.