Structure of the rat α 2 -macroglobulin-coding gene

Rat α 2 -macroglobulin ( α 2 M) is an acute-phase protein i.e., produced upon tissue inflammation. Genomic DNA clones covering the entire sequence of the α 2 M gene were isolated and characterized by restriction mapping, Southern blotting and (partial) DNA sequencing. The rat α 2 M gene is approx. 50 kb in length and consists of 36 exons ranging in size from 21 to 229 bp. Two functional domains, a bait region and a thiol ester site, are encoded by the exon 18 and 24, respectively. Several possible regulatory signals such as a TPA-inducible enhancer core, an identifier sequence, purine-pyrimidine alternative stretches and viral enhancer core sequences were identified. Several genomic DNA clones which cross-hybridized with the α 2 M cDNA probe were also identified. Sequence analysis showed that they possessed sequences identical to a part of the rat α 1 -inhibitor III cDNA and that they had a strikingly similar exon organization to the α 2 M gene.