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A set of growth arrest-specific (gas) genes whose expression is negatively regulated by serum has recently been identified. We report on the detailed analysis of one of these genes (gas3). The kinetics of regulation by the presence and absence of serum were investigated, and it was found that this gene is regulated at the post-transcriptional level. The encoded protein deduced from the nucleotide sequence showed some similarity to a mitochondrial oxyreductase, and in vitro translation established that the protein product is a transmembrane glycoprotein.

Four different polypeptides all showing a molecular weight around 70 Kd have been detected by isofocusing electrophoresis in 8M urea and further characterized by SDS polycrylamide gels and by immunoelectrophoresis. On structural grounds they can be related to a common polypeptide family; the immunological analysis strongly correlating the two most represented subunits suggests their common origin from the same native polypeptide. Their difference is probably explained by subsequent processing.