Interaction in vitro; bait produced as a recombinant fusion protein in bacterial system; prey derived from wild-type embryonic extract.

Recombinant purified ProtA and ProtB were mixed with DNA to generate "model sperm chromatin", then incubated with an embryonic extract capable of evicting protamines from DNA. This mixture was fractionated by sucrose gradient, and fractions containing evicted protamines were subjected to anti-V5 immunoprecipitation of tagged protamine. Purified endogenous proteins were identified by mass spectrometry.