Purification of antithrombin III mRNA and cloning of its cDNA.

Antithrombin III mRNA was enriched from a baboon liver by specific polysome immunoprecipitation. The partially purified antithrombin III mRNA preparation was used for cDNA synthesis and cloning. Candidate antithrombin III cDNA clones were identified by differential hybridization using as probes [32P]cDNAs synthesized from the polysome-enriched and -depleted RNA fractions, respectively. The candidate clones were further analyzed by hybrid-selected translation. The authenticity of a cDNA clone positive to both tests was unambiguously confirmed by matching its nucleotide sequence with the known amino acid sequence of human antithrombin III. The baboon antithrombin III cDNA clone hybridized well with human antithrombin III mRNA and can be used as a probe to isolate the corresponding human gene.