This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kang, Y.-J. Articles by Busch, H. Search for Related Content PubMed PubMed Citation Articles by Kang, Y.-J. Articles by Busch, H.

Nucleolar Phosphoproteins of Normal Rat Liver and Novikoff Hepatoma Ascites Cells¹

Nuclear Protein Laboratory, Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77025

The nucleolar acid-soluble proteins from normal rat liver and Novikoff hepatoma ascites cells were labeled in vivo for 2 hr after the injection of [³²P]orthophosphate and in vitro with [-³²P]adenosine triphosphate in systems containing 0.25 M sucrose, 5 mM MgCl₂, 12.5 mM NaCl, and 0.05 M Tris-HCl buffer, pH 7.3, at 37°. Two-dimensional polyacrylamide gel electrophoresis and autoradiography showed that approximately 40 and 20 protein spots were labeled in vivo and in vitro, respectively. There were some marked differences in labeling in vivo between normal rat liver and Novikoff hepatoma acid-soluble nucleolar proteins. By ³²P analysis of gel slices, the proportion of the total ³²P incorporated into protein Spot A1–4 was greater in normal liver, and the proportion of ³²P incorporated into some high-molecular-weight protein spots, such C23–24 and C26–27, was greater in the Novikoff hepatoma ascites cells. With the in vitro incubation system, the ³²P uptake per mg protein was about twice as high in Novikoff hepatoma nucleolar proteins as in normal rat liver nucleolar proteins but, generally, the same proteins were labeled in both tissues.

¹ This study was supported by USPHS Center Grant CA-10893 and by a generous gift from Mrs. Jack Hutchins.

Received 11/ 5/74. Accepted 3/ 5/75.