PURPOSE. To characterize a novel gene, deleted in polyposis 1-like 1 (Dp111), which is expressed in the retina. METHODS. A systematic screening by subtraction hybridization of the cDNAs from mouse retina and mouse brain was performed to obtain novel genes expressed in the retina. In situ hybridization, immunohistochemistry, and intracellular localization analyses were performed to investigate the expression patterns of Dp111. The chromosomal location of Dp111 was determined by radiation hybrid mapping. Bioinformatics was used for homology analysis. RESULTS. A novel gene, Dp111, was expressed abundantly in the retina. It encodes a 201-amino-acid protein, and the encoded protein is designated mouse TB2-like 1. It is highly homologous to the mouse TB2, which is encoded by deleted in polyposis 1 (Dp1). In situ hybridization and immunohistochemical analyses showed that Dp111 mRNA and the TB2-like 1 were localized richly in retinal ganglion cells (RGCs). TB2-like 1 was present in the cytoplasm in a punctate pattern. Dp111 was mapped to mouse chromosome 10 by radiation hybrid mapping. CONCLUSIONS. TB2-like 1 is a membrane protein that belongs to the YOP1/TB2/DP1/HVA22 family, and it probably plays an important role in intracellular membrane trafficking in RGCs, based on the properties of other homologous proteins.