Figure 5.

Interaction of human primase with a DNA template and rNTPs during RNA synthesis initiation. The color scheme is the same as in Figure 4. The residues of p49 interacting with the DNA template and the initiating GTP are identified from the model of the initiation complex. The asterisk indicates that a main-chain atom of the amino acid forms a hydrogen bond with a nucleotide. Amino acids participating in stacking interactions with nucleotides are shown in rectangular boxes. Interactions of aspartates 109 and 111 with both rNTPs are mediated by the Mg²⁺ ions.