The cDNA for the bovine activin receptor type II (ACVR2) gene has been cloned and sequenced. It encodes a protein of 513 amino acids which is highly homologous (approximately 98% identity) to the human, mouse, and rat proteins. Using PCR analysis of bovine x hamster somatic cell lines, the ACVR2 gene was mapped to syntenic group U17, which has been localised to bovine chromosome 2. Comparative mapping has shown that the genes within U17 are also in a syntenic group on the long arm of human and sheep chromosome 2, as well as on mouse chromosome 1. This group of genes represents an evolutionarily conserved mammalian chromosomal segment. Genotyping a highly polymorphic microsatellite locus, (AT)4(GT)9(AT)11, found within an intron of this gene confirmed the localisation by linking the ACVR2-associated microsatellite to the region of chromosome 2 flanked by CSSM42 and TGLA226. This gene locus, which has the characteristics of a type I and type II mapping locus, represents the first localisation of this gene in any species to date.