The CSN3 subunit of the COP9 signalosome interacts with the HD region of Sos1 regulating stability of this GEF protein

a Scheme of the primary structure of the truncated fragments of hSos1. b The constructs in pEG202 coding respectively for the LexA fused to the HD or NDP and vector pJG4-5 alone (without CSN3) do not present β-galactosidase activity in X-Gal plates assays. Three independent colonies from each co-transformation were analyzed. c B42-activation domain fusion plasmid coding for B42-CSN3 (construct in pJG4-5) was co-transformed into yeast strain EGY48 (ura3, his3, trp1, LexAop-leu2) with the plasmid pSH18-34 (LacZ reporter with LexA-binding sites) and with LexA DNA binding domain fusion plasmids (constructs in pEG202) coding respectively for the LexA fused to the same HD, DH, PH, DH-PH, NDP fragments and for the PRII region of hSos1 (negative control). As others negative controls, plasmid pEG202 was co-transformed with pJG4-5-CSN3 (Vector？+？CSN3). Three independent colonies from each co-transformation were analyzed for β-galactosidase activity in color X-Gal plates assays. The specificity of the interactions was tested by dependence to galactose-raffinose. d LEU+ phenotype by patching these colonies in medium lacking leucin