Table 1.
Comparative overview of proteins associated with the telomerase catalytic subunit TERT.
| Telomerase Calytic Subunit (TERT) Associated Proteins. | |||||
|---|---|---|---|---|---|
| Human TERT Associated Proteins | Protein Function and Direct Interactions | References | Arabidopsis TERT Associated Proteins | Protein Function and Direct Interactions | References |
| TERT | Catalytic subunit of telomerase | [48] | TERT | Catalytic subunit of telomerase | [49] |
| POT1 | Shelterin. Int.: telomeric ssDNA, TPP1 and CTC1. | [50,51,52,53,54] | POT1a | Shelterin-like. Int.: TERT, telomeric ssDNA, TER1, TRFL9, CBF5, RuvBL1, CTC1 and STN1. | [47,55,56,57,58] |
| TRF1 | Shelterin. Int.: telomeric dsDNA, TIN2, TANK1, PINX1, and ATM. | [59,60,61,62,63] | TRB1-3 | Shelterin-like. Int.: TERT, telomeric dsDNA, POT1b, RuvBL1 and RuvBL2a. | [64,65,66,67,68,69,70,71] |
| TRF2 | Shelterin. Int.: telomeric dsDNA; TIN2, NBS1, RAD50, Apollo, Ku70, PARP1, XPF-ERCC1, BLM, FEN1, POLB, ORC, RTEL1, ATM and HP1. | [61,72,73,74,75,76,77,78,79,80] | TRP1 | Possible non-telomeric functions of telomerase. Int.: TERT, telomere dsDNA in vitro, ARM, Ku70 and TRFL9. | [66,69,81,82,83] |
| TRFL2 | Possible non-telomeric functions of telomerase. Int.: TERT, telomere dsDNA in vitro and ARM. | [69,83] | |||
| TRFL11 | Associates with TERT. | [84] | |||
| KPNA1 | Promotes nuclear import of the TERT. | [85] | ImpA4 | Associates with TERT. | [84] |
| NCL | Involves nucleolar localization of TERT. | [86] | NUC-L1 | Role in telomere maintenance and telomere clustering. | [87,88] |
| pontin | Telomerase assembly. Int.: TERT and dyskerin. | [89] | RuvBL1 | Associates with TERT via TRBs, regulates telomerase activity. | [84,90] |
| reptin | Telomerase assembly. Int.: dyskerin. | [89] | RuvBL2a | Associates with TERT via TRBs, regulates telomerase activity. | [84] |
| ARMC6 | Int.: TRF2, telomerase. | [69,91] | ARM | May reflect posible non-telomeric functions of telomerase. Int.: TERT, TRP1, TRFL2, TRFL9 and CHR19. | [69,92] |
| TPP1 | Shelterin, mediates telomerase recruitment. Int.: TERT, POT1, TIN2, CTC1 and STN1. | [51,52,53,54,75] | n.a. | ||
| PINX1 | Potent telomerase inhibitor. Int.: TERT and TRF1. | [62] | n.a. | ||
| HOT1 | Int.: telomeric dsDNA, active telomerase. | [93] | n.a. | ||
| Ku70/80 | Int.: TERT, TR, TRF2 and RAP1. | [94,95] | Ku70/80 | Role in telomere length regulation, may protect blunt-ended telomeres Int.: TRP1, TER2 and TER2s. | [82,96,97,98,99,100,101] |
| Hsp90 | TERT assembly. Int.: TERT. | [102] | Hsp90 | NP_194150.1 | [103] |
| p23 | TERT assembly. Int.: TERT. | [102] | p23 | CAC16575, NP_683525 | [104] |
| Purα | p.h. Unwinds dsDNA telomeric oligonucleotides. | [105] | PURα1 | Associates with TERT. | [84] |
| SMARCAD1 | p.h. SWI/SNF-like protein that presumably associates with telomeres. | [106,107] | CHR19 | May reflect possible non-telomeric functions of telomerase. Int.: TERT, ARM, TRB1 and TRFL9. | [69] |
| PABPN1 | Promotes poly(A)-dependent TR 3′ end maturation. | [108] | RRM | Associates with TERT. | [92,109] |
| MT2A | p.h. Int.: HOT1. | [110,111] | MT2A | Associates with TERT. | [84,109] |
| PA2G4 | NP_006182.2 | [112] | G2p | Associates with TERT. | [84,109] |
The proteins depicted in grey are involved in telomere maintenance, however, their association with telomerase has not been described. The proteins in green are structural homologous to their human/plant counterparts, however, any involvement in telomere maintenance or association with telomerase has not been described so far. Direct interaction partners (Int.) of TERT-associated proteins are enumerated. Cases with not yet identified sequence homologues are denoted with n.a. ATP-dependent DNA helicase 2 subunit 1 and 2 (Ku70/80); Origin recognition complex (ORC); RuvB-like 2 (reptin); TIN2- and POT1-organizing protein (TPP1); TRF1-interacting nuclear protein 2 (TIN2); TRF1-interacting protein 1 (PINX1); 5′ exonuclease Apollo (Apollo); Armadillo repeat-containing protein 6 (ARMC6); Armadillo/β-catenin-like repeat-containing protein (ARM); Ataxia telangiectasia mutated kinase (ATM); Bloom syndrome protein (BLM); Centromere-binding factor (CBF5); Conserved telomere maintenance component 1 (CTC1); DNA polymerase beta (POLB); DNA repair protein RAD50 (RAD50); Double strand DNA (dsDNA); Excision repair cross-complementation 1 (ERCC1); Flap endonuclease 1 (FEN1); H/ACA ribonucleoprotein complex subunit DKC1 (dyskerin); Heterochromatin protein 1 (HP1); Homeobox telomere-binding protein 1 (HOT1); Hsp90 co-chaperone (p23); Chromatin remodeling 19 (CHR19); Importin-α5 (KPNA1); Importin subunit alpha-4 (ImpA4); Metallothionein-like 2A (MT2A); Nijmegen breakage syndrome protein 1 (NBS1); Nucleolin (NCL); Nucleolin like 1 (NUC-L1); Heat shock protein HSP 90 (Hsp90); Poly(ADP-ribose) polymerase 1 (PARP1); Polyadenylate-binding protein (PABPN1); Proliferation-associated 2G4 (PA2G4); Proliferation-associated protein (G2p); Protection of telomeres 1 (POT1); Protection of telomeres 1a, b (POT1a, b); Pur-alpha 1 (Purα1); Regulator of telomere elongation helicase 1 (RTEL1); RNA recognition motif (RRM); RuvB-like 1 (pontin); RuvB-like 1, 2a (RuvBL1, 2a); Single strand DNA (ssDNA); Suppressor of cdc thirteen homolog (STN1); SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A containing DEAD/H box 1 (SMARCAD1); Tankyrase 1 (TANK1); Telomerase reverse transcriptase (TERT); Telomerase RNA (TR); Telomerase RNA subunit 1 (TER1); Telomere repeat-binding factor 1, 2, 3 (TRB1, 2, 3); Telomere repeat-binding protein 1 (TRP1); Telomeric repeat binding factor 1-like 2, 9, 11 (TRFL 2, 9, 11); Telomeric repeat-binding factor 1, 2 (TRF1, 2); Xeroderma pigmentosum group F (XPF1); putative homolog according to NCBI blastp (p.h.).