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Biomedical subjects

M O Olson

Publications and source records attributed to M O Olson.

At least 73 records · Page 4Linked to original sources
PubMed1980

Phosphodipeptide analysis of nonhistone nuclear proteins from Novikoff hepatoma ascites cells.

To study the sites of phosphorylation in nuclear proteins a simple method was developed for the isolation and analysis of phosphodipeptides. Partial acid hydrolysates of unfractionated nonhistone nuclear proteins were subjected to Dowex-1 column chromatography followed by paper electrophoresis at pH 1.8. Phosphoserine- and phosphothreonine-containing dipeptides each had characteristic mobilities in the latter system. By subtractive Edman degradation these peptides were identified as having the general structure, X-PSer or X-PThr, where X is a nonphosphorylated amino acid. The two groups of phosphodipeptides were further purified into unique peptides by two-dimensional paper electrophoresis at pH 3.6 and 6.5. Amino acid analysis, and thus nearest neighbor analysis, of phosphodipeptides from nonhistone nuclear proteins revealed that a heterogeneous group of amino acids was on the amino terminal side of phosphoserine residues. In contrast, phosphothreonine residues were predominantly preceded by proline.

Amino Acids↗
PubMed1979

Amino acid sequence and sites of phosphorylation in a highly acidic region of nucleolar nonhistone protein C23.

Novikoff hepatoma nucleolar nonhistone proteins, C23 and B23, contain highly acidic phosphorylated regions (Mamrack, M. D., et al. (1977) Biochem. Biophys. Res. Commun. 76, 150--157). Tryptic peptides from protein C23 containing these regions were purified by DEAE-Sephadex columns and paper electrophoresis at pH 1.8. One of these, peptide C23-Ca, was sequenced by combined automated and conventional methods. The proposed amino acid sequence is shown in eq 1. This peptide was found in three 32P-labeled forms with phosphoryl groups at positions 8 and 25, and probably 28. The highly acidic sequences adjacent to the phosphorylation sites represent a unique class of phosphorylation sites different from those in histones or substrates for cytoplasmic cAMP-dependent kinases. Ala-Ala-Pro-Ala-A5la-Pro-Ala-Ser-Glu-A10sp-Glu-Asp-Glu-Glu-A15sp-Asp-Asp-Asp-Glu-A20sp-Asp-Asp-Asp-Asp-S25er-Gln-Glu-Ser-Glu-G30lu-Glu-Asp-Glu-Glu-V35al-Met-Glu-Ile-Thr-P40ro-Ala-Lys (1).

Amino Acid Sequence↗
PubMed1978

Nucleolar phosphoprotein phosphatase from Novikoff hepatoma and rat liver: characterization and partial purification.

Phosphoprotein phosphatase which dephosphorylates 32P-labeled nucleolar protein substrates was found in nucleoli of Novikoff hepatoma ascites cells and normal rat liver. The activity was extracted in high yield from nucleoli with 0.01 M Bis/Tris (pH 7.0). Low ionic strength was also required for activity: the activity was only 50% of maximum in 0.075 M NaCl. Activity was affected differently by various divalent cations: MgCl2 had little effect: CaCl2, MnCl2 and CoCl2 above 4 mM inhibited the activity 30--60%; ZnCl2 above 2 mM completely destroyed the activity. EDTA had no effect, indicating that divalent cations are probably not required. The enzyme activity was enhanced 20% by 5--8 mM dithiothreitol and was inhibited 60% by 7--10 mM N-ethylmaleimide indicating a requirement for free sulfhydryl groups. The Km of the extracted enzyme for 32P-labeled nucleolar protein was 0.6 mg/ml. The phosphatase was capable of dephosporylating the major phosphorylated nucleolar proteins C23-24 and B23-24 and also histone H1. The enzyme was purified more than 200-fold on hydroxyapatite followed by DEAE-Sephadex, which resolved the activity into three major components. The activity of enzyme extracted from Novikoff hepatoma nucleoli was approximately 2.5 times greater than from normal liver nucleoli.

Animals↗
PubMed1978

Purification and partial characterization of protein 35/7.7 a cytosol protein that is abundant in rapidly growing hepatomas.

Protein 35/7.7 is an abundant cytosol protein of Morris hepatoma 3924A and Novikoff hepatoma which was not found in normal liver. Protein 35/7.7 was isolated from the cytosol of Novikoff hepatoma ascites cells by ammonium sulfate precipitation and DEAE-cellulose chromatography. It migrated as a single major spot on two-dimensional isoelectric focusing-SDS polyacrylamide gels. The N-terminal hexapeptide is Val-Asx-Pro-Thr-Val-Phe and its carboxyl-terminal amino acid is phenylalanine.

Amino Acid Sequence↗
PubMed1976

The NH2- and COOH-terminal amino acid sequence of nuclear protein A24.

The NH2- and COOH-terminal sequence of nuclear portein A24 has been determined by automatic Edman degradation and carboxypeptidase A and B digestion. Protein A24 is of interest because it is composed in part of histone 2A (Goldknofp, I.L., and Busch, H., (1975) Biochem, Biophys. Res. Commun. 65, 951-960). The sequence of the first 37 NH2-terminal residues is: Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly-Lys-Thr-Ile-Thr-Leu-Glu-Val-Glu-Pro-Ser-Asp-Thr-Ile-Glu-Asn-Val-Lys-Ala-Lys-Ile-Gln-Asp-Lys-Glu-Gly-Ile-Pro- This sequence is not homologous to any known histone sequence. It contains regions of internal homology (italics). The COOH-terminal amino acid sequence is the same as that of histone 2A, naely: -His-His-Lys-Ala-Lys-Gly-Lys-COOH.

Amino Acid Sequence↗
PubMed1975

Isolation and characterization of protein A24, a "histone-like" non-histone chromosomal protein.

In earlier studies, the nucleolar levels of protein A24 were found to be markedly decreased in the nucleolar hypertrophy induced by thioacetamide or during liver regeneration (Ballal, N.R., Goldknopf, I.L., Goldberg, D.A., and Busch, H. (1974) Life Sci. 14, 1835-1845; Ballal, N.R., Kang, Y.-J., Olson, M.O.-J., and Busch, H.J. Biol. Chem. 250, 5921-5925). To determine the role of protein A24, methods were developed for its isolation in highly purified form. Milligram quantities of highly purified protein A24 were isolated from the 0.4 N H2SO4-soluble proteins of calf thymus chromatin by exclusion chromatography on Sephadex G-100, followed by preparative polyacrylamide gel electrophoresis. Protein A24 was highly purified as shown by its migration as a single spot on two-dimensional polyacrylamide gel electrophoresis, its single NH2-terminal amino acid, methionine, and the production of approximately 50 peptides by tryptic digestion. Like histones 2A, 2B, 3, and 4. A24 was extractable from chromatin with 0.4 N H2SO4 or 3 M NaCl/7 M urea, but unlike most non-histone proteins or histone 1, protein A24 was not extracted with 0.35 M NaCl, 0.5 M HClO4, or 0.6 M NaCl. Protein A24 was present in only 1.9% of the total amount of histones 2A, 2B, 3 and 4; its molecular weight is 27,000.

Amino Acids↗
PubMed1975

Changes in nucleolar proteins and their phosphorylation patterns during liver regeneration.

Two-dimensional polyacrylamide gel electrophoresis of nucleolar proteins of rat liver revealed marked changes at various times after partial hepatectomy. Some of the non-histone protein spots including A11, A24, A25, C13, and C14 decreased in size and density. Others, including A15, B13, B16, B18, B24-25, B27, B33, B34, C1, C2, C8, C11, C17, and C23-24 were markedly increased in size and density. In vitro labeling of the nucleoli using [gamma-32P]ATP and subsequent analysis of the proteins by two-dimensional gel electrophoresis and autoradiography indicated that the uptake of 32P into proteins increased greatly during regeneration. In addition, the relative labelling of various spots changed throughout the regeneration process. With spot B33 as a reference, there was increased labeling of spots A1P, B2, B5, B24-25, C2, and C23-24 at 8 hours after hepatectomy. On the other hand, the labeling of spots A8P, A16, A20, B9, and B13 decreased at 8 hours after hepatectomy. Since the primary role of the nucleolus is the snythesis of ribosomal precursors, these changes in protein content and phosphorylation are presumably primarily associated with the increased processing and transport of peribosomal ribonucleoproteins in regenerating liver.

Adenosine Triphosphate↗
PubMed1975

Nucleolar phosphoproteins of normal rat liver and Novikoff hepatoma ascites cells.

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 [gamma-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 DEGREES. 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.

Animals↗