Fig. 1. B-factor distribution and crystal packing of Runt domain–CBFβ heterodimers. Six Runt domain subunits and four CBFβ subunits are packed in alternating layers in the crystal. One layer is composed of two dimers of heterodimers (F+E, G+H; B+A, C+D), and the second comprises a single Runt domain homodimer (Q+R). The subunits are represented as C_α traces, and are coloured according to temperature (B) factors. Colours are graded blue (≤30 Å²) through to red (≥70 Å²). Runt domain subunits are labelled A, C, E, G, Q and R; CBFβ subunits are labelled B, D, F and H. The view is down the b-axis with a, c and crystallographic 2₁ axes indicated.