PURIFICATION OF TETRAHYMENA TELOMERASE AND CLONING OF GENES ENCODING THE 2 PROTEIN-COMPONENTS OF THE ENZYME

Telomerase is a ribonucleoprotein DNA polymerase that catalyzes the de novo synthesis of telomeric simple sequence repeats. We describe the purification of telomerase and the cloning of cDNAs encoding two prote in subunits from the ciliate Tetrahymena. Two proteins of 80 and 95 kD a copurified and coimmunoprecipitated with telomerase activity and the previously identified Tetrahymena telomerase RNA. The p95 subunit spe cifically cross-linked to a radiolabeled telomeric DNA primer, while t he p80 subunit specifically bound to radiolabeled telomerase RNA. At t he primary sequence level, the two telomerase proteins share only limi ted homologies with other polymerases and polymerase accessory factors .