Mapping of Amino Acid Residues in the p34 Subunit of Human Single-stranded DNA-binding Protein Phosphorylated by DNA-dependent Protein Kinase and Cdc2 Kinase in Vitro
Human single-stranded DNA-binding protein (HSSB, also called RPA), is a heterotrimeric complex that consists of three subunits, p70, p34, and p11. HSSB is essential for the in vitro replication of SV40 DNA and nucleotide excision repair. It also has important functions in other DNA transactions, inc...
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Veröffentlicht in: | The Journal of biological chemistry 1997-05, Vol.272 (19), p.12634-12641 |
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Sprache: | eng |
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Zusammenfassung: | Human single-stranded DNA-binding protein (HSSB, also called RPA), is a heterotrimeric complex that consists of three subunits,
p70, p34, and p11. HSSB is essential for the in vitro replication of SV40 DNA and nucleotide excision repair. It also has important functions in other DNA transactions, including
DNA recombination, transcription, and double-stranded DNA break repair. The p34 subunit of HSSB is phosphorylated in a cell
cycle-dependent manner. Both Cdc2 kinase and the DNA-dependent protein kinase (DNA-PK) phosphorylate HSSB-p34 in vitro . In this study, we show that efficient phosphorylation of HSSB-p34 by DNA-PK requires Ku as well as DNA. The DNA-PK phosphorylation
sites in HSSB-p34 have been mapped at Thr-21 and Ser-33. Kinetic studies demonstrated that a phosphate residue is first incorporated
at Thr-21 followed by the incorporation of a second phosphate residue at Ser-33. We also identified Ser-29 as the major Cdc2
kinase phosphorylation site in the p34 subunit. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.272.19.12634 |