Figure 1

Structural comparison of EWS-Oct-4 alternative forms. Two different forms of the EWS-Oct-4 protein (EWS-Oct-4 and EWS-Oct-4B) and the human Oct-4 isoforms (Oct-4A and Oct-4B) are represented schematically. Amino acid (aa) positions are indicated above and below the schematic representing the proteins. In the case of EWS-Oct-4, the first 193 aa (residues 1–193) of EWS are fused to the truncated coding sequence (residues 123–360) of Oct-4A through an additional six aa sequence. This six aa sequence is encoded by the normal intron 6 of EWS in the fusion transcript that lacks the first 122 aa (residues 1–122) present in Oct-4A. In contrast, in the case of EWS-Oct-4B, the first 174 aa (residues 1–174) of EWS were fused to the POU DNA-binding domain (residues 136–360) of Oct-4A, in which neither the additional six aa sequence nor the N-terminal domain of Oct-4A is retained in EWS-Oct-4B. Functionally important domains of the Oct-4 isoforms and EWS-Oct-4 chimeras are indicated: NTD^A, the N-terminal domain of human Oct-4A; POU^A, POU DNA-binding domain (total 156 amino acids) of human Oct-4A; CTD, C-terminal domain of Oct-4; NTD^B, N-terminal domain of human Oct-4B; POU^B, POU DNA-binding domain (total 154 amino acids) of human Oct-4B; EWS (NTD), EWS N-terminal domain (residues 1–193) of EWS-Oct-4; Extra 6 aa, extra six amino acids; N, truncated N-terminal domain of Oct-4; EWS (NTD)^B, EWS N-terminal domain (residues 1–174) of EWS-Oct-4B.