Proteins were expressed and purified from bacteria.

CkIIα and Ssl proteins coelute in gel filtration at an apparent molecular mass consistent with the formation of a 130 kDa (CkIIα)2(Ssl)2 heterotetramer.

Purified proteins were combined in equimolar mixture and subjected to gel filtration analysis.

Bait protein endogenous to testis extract.

Prey derived from a transgenic line carrying a β-galactosidase-Ssl fusion construct, P{Ssl-lacZ.934}.

Protein extract was made from dissected testis of transgenic males.