The Primary Structure of Rat Parathymosin

Parathymosin has been isolated from rat thymus and from rat liver. Its primary structure is reported as follows: AcSer-Lys-Ser-Glu-Val-Glu-Ala-Ala-Ala-$\overset 10\to{\text{Glu}}$-Leu-Ser-Ala-Lys-Asp-Leu-Lys-Glu-Lys-$\ove rset 20\to{\text{Lys}}$-Asp-Lys-Val-Glu-Glu-Lys-Ala-Gly-Arg-$\ove rset 30\to{\text{Lys}}$-Glu-Arg-Lys-Lys-Glu-Val-Val-Glu-Glu-Glu-Glu-Asn- Gly-Ala-Glu-Glu-Glu-Glu-Glu-$\overset 50\to{\text{Glu}}$-Thr-Ala-Glu-(Gly3,Asx $_{7}$,Glx14)-Glu-Gly-$\overset 80\to{\text{Pro}}$-Val-Arg-Lys-Arg-Thr-Ala-Glu-Glu-Glu-Asp-Glu-Ala- Asp-Pro-Lys-Arg-Gln-Lys-Thr-$\overset 100\to{\text{Glu}}$-Asn-Gly-Ala-Ser-AlaOH. The blocking group at the NH2 terminus was identified by mass spectrometry as acetyl. Regions homologous to amino acid sequences in prothymosin α were found to be located between residues 14-20, 23-25, 33-39, 41-43, and 83-87 of parathymosin.