This study was purposed to investigate the role of integrin beta3 cytoplasmic domain in signal transduction mediated by integrin alphaIIbbeta3 and to explore the effect of integrin beta3 on signal transduction and specificity in condition without alphaIIb subunit. The fusion protein (Tac/beta3) was stably expressed in CHO cell line expressing GPIbIX, integrin alphaIIbbeta3 (IbIX/IIbIIIa-CHO cell line) by combining extracellular and transmembrane domains (Tac) of IL-2 receptor with integrin beta3 cytoplasmic domain (beta3) for formation of fusion protein (Tac/beta3). Then a series of tests were performed, including spreading and stable adhesion of IbIX/IIbIIIa-CHO cell line in solid phase fibrinogen (Fg), fibrin clot restriction and soluble fibrinogen binding, which represent outside-in and inside-out signal transduction events. The results showed that the bidirectional signal transduction mediated by alphaIIbbeta3 in IbIX/IIbIIIa-CHO/Tac-762 cells stably expressing Tac/beta3 was seriously inhibited. It is concluded that the Tac/beta3 can play a significant role in IbIX/IIbIIIa-CHO/Tac-762 cells through a dominant negative mode, the independent presence of beta3 subunit cytoplasmic domain can regulate the bidirectional signal transduction mediated by integrin alphaIIbbeta3.