000114173 001__ 114173
000114173 005__ 20181203021019.0
000114173 037__ $$aARTICLE
000114173 245__ $$aTelomerase and the chromosome end replication problem
000114173 269__ $$a1997
000114173 260__ $$c1997
000114173 336__ $$aJournal Articles
000114173 500__ $$aHoward Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215, USA.
000114173 520__ $$aTelomerase, the enzyme that extends chromosomal DNA ends in most eukaryotes, contains essential RNA and protein subunits. We have been studying telomere replication in hypotrichous ciliates such as Euplotes aediculatus, which have numerous short macronuclear DNA molecules and therefore are highly enriched in telomeres and in telomerase. Cloning and sequencing genes for the RNA subunits from several ciliates revealed that telomerase RNAs with insignificant nucleotide sequence homology nevertheless form a common secondary structure. Affinity chromatography based on the sequence of the RNA subunit was used to purify the Euplotes telomerase as an active ribonucleoprotein enzyme. Two protein subunits, 123 kDa and 43 kDa, were identified. The finding of a yeast homologue to the 123 kDa subunit suggests that telomerase protein components may be much more highly conserved in evolution than the RNA subunits. The purified Euplotes telomerase has no activity with blunt-ended DNA primers, but instead requires a four to six nucleotide single-stranded 3' tail. This result supports a model for telomere replication in which other activities such as helicases or nucleases activate replicated DNA for extension by telomerase, a model that may be applicable to telomere replication in diverse eukaryotes.
000114173 700__ $$aCech, T. R.
000114173 700__ $$g168670$$aLingner, J.$$0240570
000114173 773__ $$j211$$tCiba Found Symp$$q20-8; discussion 28-34
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000114173 937__ $$aUPLIN-ARTICLE-1997-005
000114173 970__ $$a47/UPLIN
000114173 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000114173 980__ $$aARTICLE