21.6 Homeodomains bind related targets in DNA N-terminal am lies in minor groove Helices 1 &2 lie above the dna Figure 21 12 Helix 3 of the homeodomain binds in the major groove of DNA with helices I and 2 lying outside the double helix Helix 3 contacts both the phosphate backbone and specific bases. The N- terminal arm lies in the minor groove, and makes additional contacts Helix 3 lies in the wide groove 消当Figure 21.12 Helix 3 of the homeodomain binds in the major groove of DNA, with helices 1 and 2 lying outside the double helix. Helix 3 contacts both the phosphate backbone and specific bases. The N￾terminal arm lies in the minor groove, and makes additional contacts. 21.6 Homeodomains bind related targets in DNA