Interaction in vitro; bait produced as a recombinant fusion protein in bacterial system; prey peptide chemically synthesized and labeled in vitro.

The HP1b chromoshadow domain binds woc with Kd = 1.98 uM.

The HP1b C-terminal extension domain (aa 161-240) provides binding discrimination: it reduces the affinity of the HP1b chromoshadow domain for woc, but slightly increases binding to Su(var)2-HP2.