DNA-dependent protein kinase is activated by nicks and larger single-stranded gaps.
J Biol Chem
; 269(24): 16684-8, 1994 Jun 17.
Article
in En
| MEDLINE
| ID: mdl-8206988
ABSTRACT
DNA-PK is a DNA-activated serine/threonine protein kinase capable of phosphorylating a number of nuclear DNA-binding proteins. Purified human DNA-PK has two subunits, a 350-kDa polypeptide, Prkdc, which binds ATP and is presumed to contain the catalytic site, and the Ku autoantigen which mediates DNA binding and activation. Previous studies have shown that DNA-PK is activated in vitro by linear double-stranded DNA fragments; however, the Ku subunit binds a broader range of DNA structures. Here we show that EBP-80, a protein originally isolated as a transcription factor for a retroviral long terminal repeat element and subsequently found to be similar to if not identical with Ku, also mediates kinase activation. The EBP-80-Prkdc complex is activated by nanomolar concentrations of DNA constructs containing single-to-double strand transitions, including a closed stem-loop structure and single strand gaps of 0 (nick), 6, and 30 nucleotides. Kinase activation parallels the ability of EBP-80 to bind these and other constructs. Our results extend the range of DNA configurations known to activate DNA-PK and are consistent with the participation of this enzyme complex in several nuclear functions.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
DNA
/
Protein Serine-Threonine Kinases
/
DNA Helicases
/
Antigens, Nuclear
Limits:
Humans
Language:
En
Journal:
J Biol Chem
Year:
1994
Document type:
Article