We identified a novel cDNA related to that of transcriptional enhancer factor-1 (TEF-1) during the course of isolation and characterization of cDNAs, whose mRNAs are preferentially expressed in the mouse neural precursor cells. The putative polypeptide, termed embryonic TEA domain-containing factor (ETF), deduced from the nucleotide sequence contains 445 amino acids and shares 66% amino acid identity with mouse and human TEF-1 proteins. The primary structure of the TEA domain, a probable DNA-binding domain, and the specific DNA binding activity to the GT-IIC motif of ETF are indistinguishable from those of the known vertebrate TEF-1 proteins. However, the expression of the ETF gene is strictly regulated in developing embryos and is limited to certain tissues, such as the hindbrain of a 10-day-old mouse embryo, in contrast to the ubiquitous expression pattern of the TEF-1 gene. These results suggest that ETF is a novel mammalian member of the TEA domain-containing transcription factor family and may be involved in the gene regulation of the neural development. We have discussed the possible existence of multiple subtypes of the mammalian TEF-1 family proteins, which may play different roles in cellular and development gene regulation.