| Abstrakt: |
A novel human homeobox gene related to the mouse Esx1homeobox gene, which we have designated ESXR1,has been identified. ESXR1 and Esx1 share 65% identity within their homeodomains and have glutamic acid-rich and proline-rich N- and C-terminal regions, respectively. Unlike Esx1, ESXR1 contains 12 repeats of a unique nine amino acid motif, PPMAP(V/L)PPG, located C-terminal to the homeodomain. The general exon–intron structures of ESXR1and Esx1appear to be conserved. ESXR1has been localized to human Xq22.1–q22.3, the same region of synteny shared by the map position of Esx1. ESXR1expression appears to be restricted to the placenta and testis, the tissues in which Esx1is also expressed. These data suggest that ESXR1may be the orthologue of Esx1.The findings that there are similarities between ESXR1and Esx1,yet differences between their encoded products, are consistent with the idea that placental genes evolve rapidly between mammalian species. |
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