OBJECTIVE: To explore the protein factors that could interact with G beta subunit within the G protein signal transducing pathway. METHODS: The highly sensitive protein-protein interaction system--Yeast Two-hybrid System was applied to screen the human cDNA library with constructed XBite plasmidX containing G beta subunit gene fragment. And then the false positive test was adapted. RESULTS: Three positive gene fragments were obtained. One codes for XActin bundling proteinX. The other two are new ones and their GeneBank accession numbers are AF288405 and AF288406 respectively. CONCLUSIONS: It is the first time to find that among human brain tissue, G beta subunit becomes a structural or functional unit interacts with actin bundling protein and the other two unknown protein factors to activate the following pathway. This result may be important to understand the relationship between the actin cytoskeleton and G proteins.