Document Detail

Observation of multiple isoforms and specific proteolysis patterns of proliferating cell nuclear antigen in the context of cell cycle compartments and sample preparations.
MedLine Citation:
PMID:  12833516     Owner:  NLM     Status:  MEDLINE    
The proliferating cell nuclear antigen (PCNA) is an essential component for eukaryotic chromosomal DNA replication and repair. PCNA forms a homotrimer ring, which may function as a DNA sliding clamp for DNA polymerases and, possibly, a docking station for other replication- and repair-related proteins. Several reports have suggested the existence of different PCNA isoforms. Here we confirm, using high resolution two-dimensional electrophoresis with narrow pH ranges, the existence of three PCNA isoforms in both Chinese hamster and human breast cancer cells. Among the three isoforms, M or main form is the dominant one throughout the cell cycle while the relative amounts of the minor components A (acidic) and B (basic) forms appear to vary during the cell cycle. We also observed that a specific pattern of PCNA proteolysis occurred during isoelectric focusing in spite of high urea (8 M) and detergent (2% 3-[(3-cholamidopropyl)dimethylamino]-1-propane sulfonate), which was largely inhibited by the proteosome inhibitor MG132 or boiling. Interestingly, the proteolysis pattern was mainly observed with samples isolated from cells in S and G2 phases. A similar but much lower level of PCNA proteolysis also occurred in vivo within the nuclei of the cells in S phase. Taken together, our data are consistent with the idea that the existence of the different isoforms and specific proteolysis of PCNA are relevant to its functions in vivo.
Stanislav N Naryzhny; Hoyun Lee
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proteomics     Volume:  3     ISSN:  1615-9853     ISO Abbreviation:  Proteomics     Publication Date:  2003 Jun 
Date Detail:
Created Date:  2003-06-30     Completed Date:  2004-03-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101092707     Medline TA:  Proteomics     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  930-6     Citation Subset:  IM    
Northeastern Ontario Regional Cancer Centre, Ontario, Canada.
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MeSH Terms
Apoptosis / radiation effects
Breast Neoplasms / metabolism*
CHO Cells
Cell Cycle*
Cell Line, Tumor
Electrophoresis, Gel, Two-Dimensional
Gamma Rays / adverse effects
Hydrogen-Ion Concentration
Isoelectric Focusing
Proliferating Cell Nuclear Antigen / genetics,  isolation & purification,  metabolism*,  radiation effects
Protein Isoforms / genetics,  isolation & purification,  metabolism*,  radiation effects
Reg. No./Substance:
0/Proliferating Cell Nuclear Antigen; 0/Protein Isoforms

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