RTP - A CANDIDATE TELOMERE PROTEIN THAT IS ASSOCIATED WITH DNA-REPLICATION

In this paper we describe the isolation and characterization of rTP, t he replication Telomere Protein, formerly known as the telomere protei n homolog. The rTP was initially identified because of its homology to the gene for the Oxtricha telomere-binding protein a-subunit. The pro tein encoded by the rTP gene has extensive amino acid sequence identit y to the DNA-binding domain of the telomere-binding proteins from both Euplotes crassus and Oxytricha nova. We have now identified the prote in encoded by the rTP gene and have shown that it differs from the tel omere-binding protein in its abundance, solubility and intracellular l ocation. To learn more about the function of rTP, we determined when d uring the Euplotes life cycle the gene is transcribed. The transcript was detectable only in nonstarved vegetative cells and during the fina l stages of macronuclear development. Since the peak transcript level coincided with the rounds of replication that take place toward the en d of macronuclear development, it appeared that rTP might be involved in DNA replication. Immunolocalization experiments provided support fo r this hypothesis as antibodies to rTP specifically stain the replicat ion bands. Replication bands are the sites of DNA replication in Euplo tes macronuclei, Our results suggest that rTP may be a new telomere re plication factor.