FIGURE 3.

Overall structure of Erv1FL. A, cartoon representation of Erv1FL dimer (subunit A, cyan; subunit B, magenta). The broken lines indicate the residues between NTD and CTD that could not be modeled into the electron density map. Cys³³ of NTD and Cys¹³⁰′ of CTD′ form a disulfide bond. B, stereo view of the 2F_o − F_c electron density map contoured at 1.00′ around the mixed disulfide bond between Cys³³ of subunit A and Cys¹³⁰′ of subunit B. The Cys³³ and Cys¹³⁰′ are shown as sticks and sulfur atoms colored yellow. C and D, hydrogen bonds (C) and hydrophobic interactions (D) between NTD of subunit A and CTD′ of subunit B. The backbone of protein is presented as a semitransparent cartoon. E, superposition of the individual core domain (yellow) and that of Erv1FL subunit B (magenta).