title: Endogenous DNA-directed DNA synthesising system in a microsomal fraction of embryonic chick brain.
abstract: A DNA polymerising complex directed by endogenous DNA has been partially purified from 11-day-old embryonic chick brain microsomes by DEAE-cellulose and phosphocellulose column chromatography. The active fractions are eluted together with an exogenous DNA-directed DNA polymerase; after Sephadex gel filtration, the endogenous activity remains associated with a high molecular weight DNA-directed DNA polymerase. The endogenous activity of the complex has been shown to be RNase-resistant and actinomycin-sensitive. It requires potassium, an ATP-regenerating system and all four deoxyribonucleoside triphosphates for full activity. The significance of this activity with regard to the protovirus hypothesis is discussed.
mesh_terms: D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis*; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification* / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D003854:Deoxyribonucleotides / Q000494:pharmacology; D008861:Microsomes / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D012260:Ribonucleases
chemical_list: D003854:Deoxyribonucleotides; D003609:Dactinomycin; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D012260:Ribonucleases; D011188:Potassium