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Updated: Aug 26, 2026

Semi-quantitative Detection of RNA-dependent RNA Polymerase Activity of Human Telomerase Reverse Transcriptase Protein
Published on: June 12, 2018
Nucleolar protein PinX1p regulates telomerase by sequestering its protein catalytic subunit in an inactive complex
Jue Lin1, Elizabeth H Blackburn
1Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2200, USA.
Abstract:
Human TRF1-binding protein PinX1 inhibits telomerase activity. Here we report that overexpression of yeast PinX1p (yPinX1p) results in shortened telomeres and decreased in vitro telomerase activity. yPinX1p coimmunoprecipitated with yeast telomerase protein Est2p even in cells lacking the telomerase RNA TLC1, or the telomerase-associated proteins Est1p and Est3p. Est2p regions required for binding to yPinX1p or TLC1 were similar. Furthermore, we found two distinct Est2p complexes exist, containing either yPinX1p or TLC1. Levels of Est2p-yPinX1p complex increased when TLC1 was deleted and decreased when TLC1 was overexpressed. Hence, we propose that yPinX1p regulates telomerase by sequestering its protein catalytic subunit in an inactive complex lacking telomerase RNA.
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