Genetic evidence that the multiple apolipoprotein A-1 isoforms are encoded by a common structural gene.

We have used a genetic structural variation of apolipoprotein A-I in mice to examine the origin of the multiple charge isoforms of the plasma protein. Apolipoprotein A-I translated in vitro from hepatic or enteric mRNA revealed that the genetic variation simultaneously alters the charge of the protein produced by both tissues. The variation also shifted the charge of the entire family of isoforms found in plasma or translated in vitro. These results indicate that the protein produced by different tissues as well as the multiple isoforms are all derived from a common structural gene by processing.