Abstract
Telomerase is a large ribonucleoprotein complex that replicates the linear chromosome ends in most eukaryotes. Large-scale preparation of the telomerase core components in vitro has long been a big challenge in this field, hindering the understanding of the catalytic mechanism of telomerase, as well as slowing down the development of telomerase inhibitors for cancer therapy. We have successfully developed a protocol for large-scale preparation of the TRBD-CR4/5 complex of the medaka telomerase in vitro, and used this method to study the high-resolution structure of the TRBD-CR4/5 complex by X-ray crystallography. This procedure may be also adapted to purify other protein-RNA complexes for structural studies.