Biological Assembly 1  

 3D View: Structure | Electron Density

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Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A 

Biological assembly 1 generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 51684.03 
• Atom Count: 3450 
• Residue Count: 467 
• Unique protein chains: 2

4B18

The crystal structure of human Importin alpha 5 with TERT NLS peptide

• DOI: 10.2210/pdb4B18/pdb

• Classification: TRANSPORT PROTEIN / PEPTIDE
• Organism(s): Homo sapiens
• Expression System: Escherichia coli BL21


• Deposited: 2012-07-08 Released: 2013-09-04 
• Deposition Author(s): Kim, K.L., Yoo, J.H., Cho, H.S.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.52 Å
• R-Value Free: 0.253 
• R-Value Work: 0.198 

Literature

Akt-Mediated Phosphorylation Increases the Binding Affinity of Htert for Importin Alpha to Promote Nuclear Translocation.

Jeong, S.A., Kim, K., Lee, J.H., Cha, J.S., Khadka, P., Cho, H., Chung, I.K.

(2015) J.Cell.Sci. 128: 2287

• PubMed: 25999477 
• DOI: 10.1242/jcs.166132


• PubMed Abstract: 
  

Telomeres are essential for chromosome integrity and protection, and their maintenance requires the ribonucleoprotein enzyme telomerase. Previously, we have shown that human telomerase reverse transcriptase (hTERT) contains a bipartite nuclear localization signal (NLS; residues 222-240) that is responsible for nuclear import, and that Akt-mediated phosphorylation of residue S227 is important for efficient nuclear import of hTERT. Here, we show that hTERT binds to importin-α proteins through the bipartite NLS and that this heterodimer then forms a complex with importin-β proteins to interact with the nuclear pore complex. Depletion of individual importin-α proteins results in a failure of hTERT nuclear import, and the resulting cytoplasmic hTERT is degraded by ubiquitin-dependent proteolysis. Crystallographic analysis reveals that the bipartite NLS interacts with both the major and minor sites of importin-α proteins. We also show that Akt-mediated phosphorylation of S227 increases the binding affinity for importin-α proteins and promotes nuclear import of hTERT, thereby resulting in increased telomerase activity. These data provide details of a binding mechanism that enables hTERT to interact with the nuclear import receptors and of the control of the dynamic nuclear transport of hTERT through phosphorylation.

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Organizational Affiliation: 

Department of Integrated Omics for Biomedical Science, Yonsei University, Seoul 120-749, Korea.

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
IMPORTIN SUBUNIT ALPHA-1	A	447	Homo sapiens	Mutation(s): 0  Gene Names: KPNA1 (RCH2)
Find proteins for P52294 (Homo sapiens) Go to Gene View: KPNA1 Go to UniProtKB:  P52294

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details
TELOMERASE REVERSE TRANSCRIPTASE	B	20	Homo sapiens	Mutation(s): 0  Gene Names: TERT (EST2, TCS1, TRT) EC: 2.7.7.49
Find proteins for O14746 (Homo sapiens) Go to Gene View: TERT Go to UniProtKB:  O14746

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.52 Å
• R-Value Free: 0.253 
• R-Value Work: 0.198 
• Space Group: C 1 2 1

Unit Cell:

Length (Å)	Angle (°)
a = 159.723	α = 90.00
b = 59.916	β = 96.29
c = 69.331	γ = 90.00

Software Package:

Software Name	Purpose
SCALEPACK	data scaling
REFMAC	refinement
MOLREP	phasing
HKL-2000	data reduction

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2012-07-08 
• Released Date: 2013-09-04 
• Deposition Author(s): Kim, K.L., Yoo, J.H., Cho, H.S.

Revision History 

• Version 1.0: 2013-09-04
  Type: Initial release
• Version 1.1: 2015-04-22
  Type: Database references
• Version 1.2: 2015-04-29
  Type: Derived calculations, Source and taxonomy
• Version 1.3: 2015-06-24
  Type: Database references
• Version 1.4: 2015-07-01
  Type: Database references