title: Purification and partial characterization of a 19kD/pI 4.5 nucleolar phosphoprotein.
abstract: Two-dimensional PAGE analysis of proteins associated with the slowly sedimenting "fibrillar" structures of HeLa nucleoli revealed a protein with a M of 19,000 and a pI of 4.5 which was highly labeled both with 32P-orthophosphate and 35S-methionine. The protein was isolated from Novikoff hepatoma nucleoli by extraction in 0.35 M NaCl and 5 mM DTT followed by chromatography in EDTA on DEAE-cellulose and Sephadex G-100. The protein was homogeneous with respect to two-dimensional PAGE, number of tryptic peptides and carboxyl terminal analysis. The protein contained an acidic/basic amino acid ratio of 2.1, 7 residues of methionine, 2 residues of cysteine, a blocked amino terminus and a carboxyl terminal lysylleucine.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001345:Autoradiography; D002466:Cell Nucleolus / Q000032:analysis*; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002621:Chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells / Q000032:analysis; D006801:Humans; D007525:Isoelectric Focusing; D008114:Liver Neoplasms, Experimental / Q000032:analysis; D008297:Male; D009698:Nucleoproteins / Q000302:isolation & purification*; D010750:Phosphoproteins / Q000302:isolation & purification*; D051381:Rats
chemical_list: D000596:Amino Acids; D009698:Nucleoproteins; D010750:Phosphoproteins