Document Detail

Modification of nucleolar protein B23 after exposure to ionizing radiation.
MedLine Citation:
PMID:  7631008     Owner:  NLM     Status:  MEDLINE    
The responses of cells to ionizing radiation include induction and/or suppression of the expression of genes and proteins. In our investigations of alterations in cellular protein expression in response to ionizing radiation, we have used the techniques of two-dimensional polyacrylamide gel electrophoresis and silver staining. We compared the nuclear protein profiles of control and irradiated (6 Gy, 4 h postirradiation) radioresistant squamous carcinoma cells (SQ-20B) and observed an alteration in the expression of a 40 kDa protein: control nuclei express a protein isoform with pI values between 5.4-5.8, while irradiated nuclei express a more acidic variant with pI values between 5.2-5.5. Using the cyanogen bromide/O-phthalaldehyde method followed by microsequencing analysis, we obtained an internal amino acid sequence and identified the 40 kDa protein as nucleolar protein B23. Western blotting experiments confirmed the internal amino acid sequencing results and showed both species (control, 5.4-5.8, irradiated, 5.2-5.5) to be recognized by an anti-B23 monoclonal antibody. Radiolabeling of control and irradiated samples with [32P]NAD or [32P]orthophosphoric acid revealed the acidic species of B23 to be both ADP-ribosylated and phosphorylated. Therefore, exposure of SQ-20B cells to radiation results in the increase in expression of an ADP-ribosylated and phosphorylated species of B23.
P Ramsamooj; V Notario; A Dritschilo
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Radiation research     Volume:  143     ISSN:  0033-7587     ISO Abbreviation:  Radiat. Res.     Publication Date:  1995 Aug 
Date Detail:
Created Date:  1995-09-05     Completed Date:  1995-09-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0401245     Medline TA:  Radiat Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  158-64     Citation Subset:  IM; S    
Department of Radiation Medicine, Lombardi Cancer Center, Georgetown University, Washington, D.C. 20007, USA.
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MeSH Terms
Adenosine Diphosphate Ribose / metabolism
Amino Acid Sequence
Cell Nucleolus
Electrophoresis, Gel, Two-Dimensional
Molecular Sequence Data
Nuclear Proteins / metabolism,  radiation effects*
Phosphoproteins / metabolism,  radiation effects*
Radiation, Ionizing
Sequence Homology, Amino Acid
Tumor Cells, Cultured
Grant Support
Reg. No./Substance:
0/Nuclear Proteins; 0/Phosphoproteins; 117896-08-9/nucleophosmin; 20762-30-5/Adenosine Diphosphate Ribose

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