Table 2.
Comparative overview of proteins associated with the RNA component of telomerase.
| Telomerase RNA Associated Proteins | |||||
|---|---|---|---|---|---|
| Human TR Associated Proteins | Protein Function and Direct Interactions | References | Arabidopsis TR Associated Proteins | Protein Function and Direct Interactions | References |
| TR | RNA subunit of telomerase | [113] | TER1, TER2, TER2s | Putative RNA subunit of telomerase | [56,100] |
| TERT | Catalytic subunit of telomerase | [48,114] | TERT | Catalytic subunit of telomerase | [100] |
| Dyskerin | H/ACA snoRNPs, associated with nucleolus. Int.: TR, GAR1, NHP2, NOP10 and TCAB1. | [44,115] | CBF5 | H/ACA snoRNPs, Ath orthologue of Dyskerin, associated with nucleolus, subnuclear bodies and Cajal bodies, associated with telomerase RNP complex. Direct interaction with either of putative TERs not demonstrated. Int.: NAF1. |
[45,57] |
| NOP10 | H/ACA snoRNPs, associates with nucleolus. Int.: TR and dyskerin. | [44,116] | NOP10 | H/ACA snoRNPs, Ath orthologue of NOP10, associates with nucleolus. |
[45,46] |
| NHP2 | H/ACA snoRNPs, associates with nucleolus. Int.: TR, dyskerin and TCAB1. | [117,118] | NHP2 | H/ACA snoRNPs, Ath orthologue of NHP2, associates with nucleolus. |
[45,46] |
| GAR1 | H/ACA snoRNPs, associated with nucleolus. Int.: dyskerin and TCAB1. |
[44,118] | GAR1, 2 | H/ACA snoRNPs, Ath orthologues of GAR1, associate with nucleolus. |
[45,46] |
| NAF1 | H/ACA snoRNPs, nucleolar shuttle - NAF1 is substituted by GAR1 during maturation of telomerase. Int.: dyskerin. | [119] | NAF1 | H/ACA snoRNPs, Ath orthologue of NAF1, associates with nucleolus and Cajal bodies. Int.: CBF5. |
[45] |
| Ku70/80 | Int.: TR, TERT, TRF2 and RAP1. | [95,120] | Ku70/80 | Role in telomere length regulation, may protect blunt-ended telomeres Int.: TRP1, TER2 and TER2s. | [100] |
| pontin | Telomerase assembly. Int.: TERT and dyskerin. | [89] | RuvBL1 | Associates with TERT via TRBs, regulates telomerase activity. | Schorova et al., submitted |
| reptin | Telomerase assembly. Int.: dyskerin. | [89] | RuvBL2a | Associates with TERT via TRBs, regulates telomerase activity. | Schorova et al., submitted |
| RHAU | RNA helicase, unwinds a G4-quadruplex in human telomerase RNA. Int.: TR. | [121] | RHAU | NP_850255.1, NP_175298.2, NP_680142.2, NP_178223.2 | n.a. |
| PARN | Poly(A)-specific ribonuclease, 3′-end maturation of the TR. Int.: TR | [122] | PARN | Poly(A) degradation activity, essential gene first required during early development. | [123] |
| TCAB1 | H/ACA snoRNPs, driving telomerase to Cajal bodies. Int.: TR, dyskerin, NHP2 and GAR1. | [124] | TCAB1 | NP_193883.2 | n.a. |
The proteins in green are structural homologues to their human counterparts, however, any involvement in telomere maintenance or association with RNA component of telomerase has not been described so far. Direct interaction partners (Int.) of TR-associated proteins are enumerated. Cases when reference is not available are denoted n.a. H/ACA ribonucleoprotein complex subunit DKC1 (dyskerin); RuvB-like 2 (reptin); Arabidopsis (Ath); ATP-dependent DNA helicase 2 subunit 1 and 2 (Ku70/80); box H/ACA small nucleolar RNA-protein complexes (H/ACA snoRNPs); Centromere-binding factor (CBF5); Glycine arginine rich 1, 2 (GAR1, 2); Non-histone protein 2 (NHP2); Nuclear assembly factor 1 (NAF1); Nucleolar protein 10 (NOP10); Repressor-activator protein 1 (RAP1); RNA helicase (PARN); RNA helicase (RHAU); RuvB-like 1 (pontin); RuvB-like 1, 2a (RuvBL1, 2a); Telomerase Cajal body protein 1 (TCAB1); Telomerase reverse transcriptase (TERT); Telomere repeat-binding factors (TRBs); Telomere repeat-binding protein 1 (TRP1); Telomerase RNA subunit 1, 2, 2s (TER1, 2, 2s); Telomeric repeat-binding factor 2 (TRF2); Telomerase RNA (TR).