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Updated: Jul 13, 2026

Semi-quantitative Detection of RNA-dependent RNA Polymerase Activity of Human Telomerase Reverse Transcriptase Protein
Published on: June 12, 2018
Targeting to the endoplasmic reticulum improves the folding of recombinant human telomerase reverse transcriptase
Chia-Kuei Wu1, Karine Gousset, Stephen H Hughes
1HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
Abstract:
Telomerase is a specialized reverse transcriptase that catalyzes the addition of telomeric repeats, TTAGGG in all vertebrates, to the ends of chromosomes. The lack of recombinant purified human telomerase reverse transcriptase (hTERT) has hampered biochemical and structural studies. The primary problem in generating active recombinant hTERT appears to be protein folding, which may be due to the fact that telomerase is a multi-component ribonucleoprotein complex. When expressed in most heterologous systems, recombinant hTERT is largely insoluble. Here we describe a protein expression system using a baculovirus vector that can be used to prepare properly folded, enzymatically active, hTERT. In this system, the recombinant hTERT is directed to the endoplasmic reticulum (ER), which is rich in chaperones. This increases the expression of soluble recombinant hTERT, promoting proper folding using intrinsic ER chaperone proteins.
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Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...

