Identification of a low-Mr acidic nuclear protein as prothymosin alpha.
We have purified to homogeneity a 15-kDa perchloric acid (PCA)-soluble protein from rat thymus nuclei. This highly acidic protein showed a Mr of ca. 30 kDa in acetic acid/urea gels, probably due to oligomer formation. Sequence analysis of internal tryptic and thermolytic peptides revealed that the purified protein is, in fact, prothymosin alpha, a very hydrophilic polypeptide, which has been previously classified as a thymic or immunomodulating hormone. We found that prothymosin alpha is a rather abundant nuclear protein in rat thymus; its concentration is comparable to that of a well-characterized nonhistone protein HMG-14. The subcellular localization and physicochemical properties of prothymosin alpha suggest that its function is related to those of other long polyacidic regions containing nuclear proteins.
Palvimo
J
J
Department of Biochemistry and Biotechnology, University of Kuopio, Finland.
Linnala-Kankkunen
A
A
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000737:chemistry; D011498:Protein Precursors / Q000737:chemistry / Q000302:isolation & purification*; D051381:Rats; D013947:Thymosin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D013950:Thymus Gland / Q000737:chemistry
D009687:Nuclear Proteins; D010446:Peptide Fragments; D011498:Protein Precursors; C040782:prothymosin alpha; D013947:Thymosin