2QB5

Crystal Structure of Human Inositol 1,3,4-Trisphosphate 5/6-Kinase (ITPK1) in Complex with ADP and Mn2+


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.181 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Integration of inositol phosphate signaling pathways via human ITPK1.

Chamberlain, P.P.Qian, X.Stiles, A.R.Cho, J.Jones, D.H.Lesley, S.A.Grabau, E.A.Shears, S.B.Spraggon, G.

(2007) J.Biol.Chem. 282: 28117-28125

  • DOI: 10.1074/jbc.M703121200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) is a reversible, poly-specific inositol phosphate kinase that has been implicated as a modifier gene in cystic fibrosis. Upon activation of phospholipase C at the plasma membrane, inositol 1,4,5-trispho ...

    Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) is a reversible, poly-specific inositol phosphate kinase that has been implicated as a modifier gene in cystic fibrosis. Upon activation of phospholipase C at the plasma membrane, inositol 1,4,5-trisphosphate enters the cytosol and is inter-converted by an array of kinases and phosphatases into other inositol phosphates with diverse and critical cellular activities. In mammals it has been established that inositol 1,3,4-trisphosphate, produced from inositol 1,4,5-trisphosphate, lies in a branch of the metabolic pathway that is separate from inositol 3,4,5,6-tetrakisphosphate, which inhibits plasma membrane chloride channels. We have determined the molecular mechanism for communication between these two pathways, showing that phosphate is transferred between inositol phosphates via ITPK1-bound nucleotide. Intersubstrate phosphate transfer explains how competing substrates are able to stimulate each others' catalysis by ITPK1. We further show that these features occur in the human protein, but not in plant or protozoan homologues. The high resolution structure of human ITPK1 identifies novel secondary structural features able to impart substrate selectivity and enhance nucleotide binding, thereby promoting intersubstrate phosphate transfer. Our work describes a novel mode of substrate regulation and provides insight into the enzyme evolution of a signaling mechanism from a metabolic role.


    Organizational Affiliation

    Genomics Institute of the Novartis Research Foundation, San Diego, California 92121, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Inositol-tetrakisphosphate 1-kinase
A, B
347Homo sapiensMutation(s): 0 
Gene Names: ITPK1
EC: 2.7.1.134
Find proteins for Q13572 (Homo sapiens)
Go to Gene View: ITPK1
Go to UniProtKB:  Q13572
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MN
Query on MN

Download SDF File 
Download CCD File 
A, B
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
ADP
Query on ADP

Download SDF File 
Download CCD File 
A, B
ADENOSINE-5'-DIPHOSPHATE
C10 H15 N5 O10 P2
XTWYTFMLZFPYCI-KQYNXXCUSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.181 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 62.704α = 90.00
b = 94.315β = 90.00
c = 130.242γ = 90.00
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-07-03
    Type: Initial release
  • Version 1.1: 2007-10-23
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Version format compliance