2Institute of Chemical Biology and Fundamental Medicine, Siberian Division of the Russian Academy of Sciences, pr. Akademika Lavrentieva 8, 630090 Novosibirsk, Russia
3Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, 119991 Moscow, Russia
4Blokhin Cancer Research Center, Russian Academy of Medical Sciences, Kashirskoe Shosse 24, 115478 Moscow, Russia
* To whom correspondence should be addressed.
Received June 18, 2008; Revision received June 30, 2008
Our aim was to investigate how replication protein A (RPA) in a wide range of concentration can regulate the activity of human telomerase. We used an in vitro system based on human cell extracts with or without RPA. It has been shown that removal of RPA leads to loss of telomerase activity and addition of RPA restores telomerase activity and at the same time promotes telomerase processivity. However, high excess of RPA inhibited telomerase processivity and caused the synthesis of relatively short DNA fragments (about 50-100 nucleotides). We assume that, together with other telomere-binding proteins, RPA may take part in activation of telomere overhang elongation by telomerase at a certain stage of a cell cycle as well as in regulation of telomere length.
KEY WORDS: telomerase, RPA, telomeres, regulation