We report preliminary characterization of a gene designated beta-R1, which is selectively expressed in response to interferon beta (IFN-beta) compared with IFN-alpha. In human astrocytoma cells, beta-R1 was induced to an equivalent extent by 10 IU/mL IFN-beta or 2500 IU/mL IFN-alpha2. To address the mechanism of this differential response, we analyzed induction of the beta-R1 gene in fibrosarcoma cells and derivative mutant cells lacking components required for signaling by type I IFNs. beta-R1 was readily induced by IFN-beta in the parental 2fTGH cell line, but not by recombinant IFN-alpha2, IFN-alpha Con1, or a mixture of IFN-alpha subtypes. IFN-alpha8 induced beta-R1 weakly. beta-R1 was not induced by IFN-beta in mutant cell lines U2A, U3A, U4A, and U6A, which lack, respectively, p48, STAT1, JAK1, and STAT2. U5A cells, which lack the Ifnar 2.2 component of the IFN-alpha and -beta receptor, also failed to express beta-R1. U1A cells are partially responsive to IFN-beta and IFN-alpha8 but lacked beta-R1 expression, indicating that TYK2 protein is essential for induction of this gene. Taken together, these results suggest that the expression of beta-R1 in response to type I IFN requires IFN-stimulated gene factor 3 plus an additional component, which is more efficiently formed on induction by IFN-beta compared with IFN-alpha.