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General Comment |
TZAP: A telomere-associated protein involved in telomere length control. Li JS et al. (2017) Telomeres are found at the end of chromosomes and are important for chromosome stability. Here, we describe a specific telomere-associated protein: TZAP (Telomeric Zinc finger-Associated Protein). TZAP binds preferentially to long telomeres that have a low concentration of shelterin complex, competing with the telomeric repeat binding factors TRF1 and TRF2. When localized at telomeres, TZAP triggers "telomere trimming," a process that results in the rapid deletion of telomeric repeats. Based on these results, we propose a model for telomere length regulation in mammalian cells: The reduced concentration of the shelterin complex at long telomeres results in TZAP binding and initiation of telomere trimming. Binding of TZAP to long telomeres represents the switch that triggers telomere trimming, setting the upper limit of telomere length.//////////////////
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