This invention provides novel hippocampus-associated proteins and DNA sequences coding therefor. In an investigation of hippocampus-associated proteins by differential screening of a rat hippocampus cDNA library, a cDNA species encoding a novel protein designated Hct-1 was isolated and shown to be a to cytochromes P450. The use of hybridization probes based on the rat Hct-1 sequence has led to the identification of homologues in other mammalian species.