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
; 29(1): 13-9, 1992 Feb.
Article
in En
| MEDLINE
| ID: mdl-1592412
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.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
DNA, Single-Stranded
/
Chromatin
/
Carcinoma, Ehrlich Tumor
/
DNA-Binding Proteins
/
Neoplasm Proteins
Limits:
Animals
Language:
En
Journal:
Indian J Biochem Biophys
Year:
1992
Document type:
Article