Primary structure of rat liver apoferritin. The amino end

Rat liver apoferritin is known to have a blocked amino end. From a pronase digest of rat liver apoferritin we have isolated and purified by ion-exchange chromatography the blocked N-terminal tripeptide. Its sequence and the nature of the blocking group were shown to be Ser-Ser-Gln and an acetyl moiety, respectively. The N-terminal sequence of rat liver apoferritin is thus N-acetyl-Ser-Ser-Gln, which coincides with the N-terminal sequence of horse-spleen apoferritin, the only other apoferritin studied structurally at present.