While investigating differences in the pattern of gene expression in functionally distinct areas of the rat caudate-putamen employing differential display, we identified a gene that is highly enriched in tissue adjacent to the lateral ventricle. To characterize the gene, a complementary DNA containing the complete coding sequence was obtained and sequenced. In addition, radiolabelled DNA and riboprobes were generated to examine the expression levels and anatomical distribution of the identified gene in the brain. The sequencing data suggests that the identified gene is a member of the heterogeneous nuclear ribonucleoprotein family and likely represents the rat homolog of CArG-binding protein A initially isolated from mouse C2 myogenic cells. CArG-binding protein A is widely distributed and moderately expressed in the rat brain and present within both neurons and astrocytes. Since the CArG box motif forms the core of the serum response element and the serum response element is involved in immediate early gene regulation, the expression level of CArG-binding protein A was examined following treatment of PC12 cells with nerve growth factor and correlated with changes in c-fos and zif268 expression. The results show that CArG-binding protein A is up-regulated following nerve growth factor treatment and that the up-regulation of CArG-binding protein A can be correlated with the down-regulation of c-fos and zif268. The results of the current study leads us to suggest that CArG-binding protein A may be involved in brain development and the regulation of the serum response element.