The symbiotic nodulation between legumes and rhizobacteria is an interactive process of exchange of signal molecules.Genes for nodulation signal pathway NSP1 and NSP2 are the essential components for nod-factor induced symbiotic signal pathway. Protein encoded by LjNSP1 and LjNSP2 includes the plant-specific GRAS domain,which are predicted to code transcription factor,but the unique biochemical evidence remains to be identified.To examine this inference,the above two genes were fused into DNA binding domain for yeast GAL4 transcription factor with yeast two hybrid.Whether or not activating expression of downstream reporter genes were utilized to test their function of transcriptional activation.Our result substantiated encoding products of these two genes possess such activation in yeast.To further determine the transcriptional activation region,a series of deletion mutants were constructed,which successfully identified the activation region belonging to the variable domain of N terminal of each protein.Yeast one -hybrid was performed to test whether LjNSP1 and LjNSP2 proteins,possess function of binding promoter for certain specified genes as transcription factor.The result showed that proteins encoded by LjNSP1 and LjNSP2 were capable of binding promoter of NIN (nodulation initiation) gene,but failed to bind that of CBP1(calcium binding protein ) gene.This study demonstrates that LjNSP1 and LjNSP2 possess function of binding particular DNA and transcriptional activation,providing important significance for the elucidation of mechanism for nod-factor induced signaling.