The telomerase RNP complex is formed in the nucleoplasm from TERT protein, TERC RNA, and DKC1 (dyskerin) protein. The complex has been identified and its activity demonstrated in chicken cells (Hrdlickova et al. 2006). Its stoichiometry and the presence of DKC1 as a component of the complex are inferred from studies of purified human telomerase RNP (Cohen et al. 2007).
RUVBL1 (pontin) and RUVBL2 (reptin) are found associated with human telomerase RNPs purified from HeLa cells, and activities of these proteins are required for telomerase RNP assembly in vivo (Venteicher et al. 2008). The exact roles of these proteins in the assembly and function of telomerase RNP in vivo remain unclear, however, so the one protein, RUVBL1 (pontin), for which a chicken ortholog has been identified is annotated simply as positively regulating telomerase RNP formation.
NHP2 (NOLA2) is likewise associated with telomerase ribonucleoprotein complexes (Pogacic et al. 2000) and homozygosity for NHP2 mutations is associated with telomerase failure (dyskeratosis congenital) in humans (Vuillamy et al. 2008). The molecular function of NHP2 remains unclear, however, so its chicken ortholog is annotated simply as positively regulating telomerase RNP formation.
The chicken TERC gene has been identified, based on its content of conserved TERC sequence elements (Chen et al. 2000) and the phenotypes of DT40 cells heterozygous for a null allele of the gene (Faure et al. 2008). Both a full-length the chicken TERT mRNA and numerous shorter mRNAs generated by alternative splicing have been described, but only the full-length form encodes a catalytically active protein (Chang and Delaney 2006; Hrdlickova et al. 2006).
