Properties of single-stranded DNA-binding proteins (SSB-proteins) from chromatin and nonchromatin fractions of Ehrlich ascites tumour: phosphorylation enhances the affinity of SSB-proteins for single-stranded DNA.
Indian J Biochem Biophys
;
1992 Feb; 29(1): 13-9
Article
in English
| IMSEAR
| ID: sea-28726
ABSTRACT
To assess the possible functional role of single-strand DNA-binding (SSB) proteins in eucaryotic cell, a comparative study was made of SSB-proteins isolated from chromatin and the nonchromatin fractions of Ehrlich ascites tumour (EAT) cells. No appreciable differences between the two groups could be found either in SDS-gel electrophoretic patterns or in the ssDNA-binding capacity and stimulation of DNA replication in permeable EAT cells. However, the chromatin SSB-proteins incorporated 1.4-times more labelled phosphate in vivo; phosphate assays in the isolated chromatin and nonchromatin SSB-proteins yielded ca. 3 and 2 moles Pi/mole protein, respectively. Both preparations could be further phosphorylated in vitro with Ca-phospholipid-dependent protein kinase and the catalytic subunit of cAMP-dependent protein kinase, but the non-chromatin proteins were phosphorylated to a greater degree. In parallel with phosphorylation, the SSB-proteins displayed stronger binding to ssDNA cellulose. Phosphorylation may thus be a means of regulating the functions of SSB-proteins, in particular their interaction with chromatin.
Full text:
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Index:
IMSEAR (South-East Asia)
Main subject:
Phosphorylation
/
Protein Binding
/
DNA, Single-Stranded
/
Chromatin
/
Carcinoma, Ehrlich Tumor
/
Cell Fractionation
/
DNA-Binding Proteins
/
Animals
/
Mice
/
Neoplasm Proteins
Language:
English
Journal:
Indian J Biochem Biophys
Year:
1992
Type:
Article
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