A novel gene, rasfadin (RASSF2) was identified close to the bovine prion gene, and its genomic structure was derived with a combination of exon trapping and RACE. The gene covers at least 28 kb and maps to the same chromosomal region as the prion gene in cattle, sheep, and human. The RASSF2 ORF is composed of 987 base pairs divided into nine exons and shows a high nucleotide (88%) and amino acid similarity (95%) with a previously described human cDNA, KIAA0168. The bovine 3'UTR region is significantly shorter than the human counterpart, but shares with it two highly conserved nucleotide blocks. The expression of the gene was investigated in brain, liver, and spleen. Alternative splicing yields a shorter product in the liver composed of only four exons. Computer analysis showed a highly significant similarity of the rasfadin protein with the Ras association (Ral-GDS/AF-6) domain family 2 and with the afadin family, respectively, for the longer brain/spleen and the shorter liver variants.