Аннотация:Telomeres are essential for genome stability in all eukaryotes. Changes in telomere functions and the associated chromosomal abnormalities have been implicated in human aging and cancer. Telomerase – is a multisubunit enzyme that provides genome sta- bility by elongation of ends of the telomeres in the immortal cells (in particular germ, stem and cancer cells). Est3 – is a small regulatory subunit of yeast telomerase which is dispensable for enzyme catalysis but essential for telomere rep- lication in vivo yeast Saccharomyces cerevisiae. We show here an identification of Est3 protein from the meth- ylotrophic yeast Hansenula polymorpha (syn.Pichia angusta). Deletion of hpEst3 gene leads to senescence phenotype and telo- mere shortening. We created a construction, which permits to obtain a protein with removable tag. The hpEst3 protein was iso- lated, cleaved and purified for further structural analysis. After several primary crystallization screens we observed the data about initial crystallization conditions. Availability of an atomic structure of the telomerase compo- nents will allow elucidation of in vivo mechanisms of telomerase action and open new possibilities for the development of novel agents for the normalization of cell division in cancer cells.