Table 2. Interaction between α and Cnr proteins detected by the yeast two-hybrid system.

Plasmidsa	Protein fused tob		Activation of lexAop6-LEU2d	Activation of lexAop8-lacZe
	LexA DNA-binding domainc	B42 activation domain	(Eop)	(U β-galactosidase)
pEG202 pJG4–5	–	–	1 × 10–3	3.16 ± 0.68
pEG202 pGM592	–	Cnr	<7 × 10–3	2.81 ± 0.97
pGM585 pJG4–5	α	–	<5 × 10–3	1.02 ± 1.12
pGM585 pGM592	α	Cnr	0.62	11.42 ± 1.20
pGM587 pJG4–5	αcrL733V	–	<4 × 10–3	2.10 ± 0.62
pGM587 pGM592	αcrL733V	Cnr	<8 × 10–3	1.74 ± 1.45
pGM588 pJG4–5	αcrG732W	–	<3 × 10–3	0.82 ± 0.40
pGM588 pGM592	αcrG732W	Cnr	<6 × 10–3	1.02 ± 0.43
pGM589 pJG4–5	αcrG732V	–	<4 × 10–3	1.52 ± 1.10
pGM589 pGM592	αcrG732V	Cnr	<7 × 10–3	2.24 ± 0.30
pGM590 pJG4–5	αcrT675M	–	<4 × 10–3	2.03 ± 0.46
pGM590 pGM592	αcrT675M	Cnr	0.14	3.80 ± 1.73

^aThe plasmids are carried by the S.cerevisiae strain EGY48 (pSH18–34).

^bThe proteins fused to either the DNA-binding domain or the transcription activation domain are indicated. The fusion proteins were expressed in S.cerevisiae EGY48 (pSH18–34) in a galactose/raffinose medium lacking uracil, hystidine and tryptophan. Three independent transformants were tested for each strain.

^cActivation and repression assays (21) confirmed that the fusion protein by itself did not activate the reporter genes and that it is localized in the nucleus (data not shown).

^dExpression of the lexAop6-LEU2 reporter gene was tested by measuring the efficiency of plating (Eop) in a galactose/raffinose medium in the presence or absence of leucine.

^eExpression of the lexAop8-lacZ reporter gene was tested by measuring the β-galactosidase specific activity. The activities are calculated as nanomoles of O-nitrophenyl galactoside hydrolyzed per minute per milligram of protein (U β-galactosidase; 37). The values are the mean of assays on three independent transformants each assayed twice.