| Furthermore , we demonstrate interaction of TFIIB with Sp1 / Sp3 at the Sp 1 ( 1 ) site besides its association with EAR 3 and the TATA less core promoter region . ^^^ We further demonstrated that EAR 3 specifically decreased association of TFIIB to the Sp 1 ( 1 ) site without interfering on its interaction with the hLHR core promoter . ^^^ The C terminal region of EAR 3 , which did not participate in its interaction with Sp 1 , was required for its inhibitory function and may affect the association of TFIIB with Sp 1 . ^^^ Moreover , perturbation of the association of TFIIB with Sp 1 by EAR 3 was reflected in the reduced recruitment of RNA polymerase 2 to the promoter . ^^^ Overexpression of TFIIB counteracted the inhibitory effect of EAR 3 and activated hLHR gene transcription in an Sp 1 site dependent manner . ^^^ |