PDBsum entry 1qoi

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protein links
Isomerase PDB id
Protein chain
173 a.a. *
Waters ×181
* Residue conservation analysis
PDB id:
Name: Isomerase
Title: U4/u6 snrnp-specific cyclophilin snucyp-20
Structure: Snucyp-20. Chain: a. Synonym: usa-cyp. Engineered: yes
Source: Homo sapiens. Human. Organism_taxid: 9606. Cell_line: hela. Organelle: nucleus. Cellular_location: nucleus. Plasmid: pgex-snucyp-20. Gene: snucyp-20. Expressed in: escherichia coli.
2.0Å     R-factor:   0.170     R-free:   0.224
Authors: U.Reidt,K.Reuter,T.Achsel,D.Ingelfinger,R.Luehrmann, R.Ficner
Key ref:
U.Reidt et al. (2000). Crystal structure of the human U4/U6 small nuclear ribonucleoprotein particle-specific SnuCyp-20, a nuclear cyclophilin. J Biol Chem, 275, 7439-7442. PubMed id: 10713041 DOI: 10.1074/jbc.275.11.7439
09-Nov-99     Release date:   10-Apr-00    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
O43447  (PPIH_HUMAN) -  Peptidyl-prolyl cis-trans isomerase H
177 a.a.
173 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Enzyme reactions 
   Enzyme class: E.C.  - Peptidylprolyl isomerase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Peptidylproline (omega=180) = peptidylproline (omega=0)
Peptidylproline (omega=180)
= peptidylproline (omega=0)
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     U4/U6 snRNP   6 terms 
  Biological process     protein complex assembly   7 terms 
  Biochemical function     protein binding     5 terms  


    Added reference    
DOI no: 10.1074/jbc.275.11.7439 J Biol Chem 275:7439-7442 (2000)
PubMed id: 10713041  
Crystal structure of the human U4/U6 small nuclear ribonucleoprotein particle-specific SnuCyp-20, a nuclear cyclophilin.
U.Reidt, K.Reuter, T.Achsel, D.Ingelfinger, R.Lührmann, R.Ficner.
The cyclophilin SnuCyp-20 is a specific component of the human U4/U6 small nuclear ribonucleoprotein particle involved in the nuclear splicing of pre-mRNA. It stably associates with the U4/U6-60kD and -90kD proteins, the human orthologues of the Saccharomyces cerevisiae Prp4 and Prp3 splicing factors. We have determined the crystal structure of SnuCyp-20 at 2.0-A resolution by molecular replacement. The structure of SnuCyp-20 closely resembles that of human cyclophilin A (hCypA). In particular, the catalytic centers of SnuCyp-20 and hCypA superimpose perfectly, which is reflected by the observed peptidyl-prolyl-cis/trans-isomerase activity of SnuCyp-20. The surface properties of both proteins, however, differ significantly. Apart from seven additional amino-terminal residues, the insertion of five amino acids in the loop alpha1-beta3 and of one amino acid in the loop alpha2-beta8 changes the conformations of both loops. The enlarged loop alpha1-beta3 is involved in the formation of a wide cleft with predominantly hydrophobic character. We propose that this enlarged loop is required for the interaction with the U4/U6-60kD protein.
  Selected figure(s)  
Figure 2.
Fig. 2. Stereo view of the superposition of the C -backbones of hCypA and SnuCyp-20. hCypA is shown in red and SnuCyp-20 is blue. The superposition was created using the program VMD (35).
Figure 3.
Fig. 3. Stereo view of residues Cys47 and Cys174 superimposed with the 2 F[o] F[c] electron density map. The electron density map (contoured at 1.5 ) clearly shows the reduced form of Cys47 and Cys174 consistent with the growth of the crystals in the presence of 2 mM DTT.
  The above figures are reprinted by permission from the ASBMB: J Biol Chem (2000, 275, 7439-7442) copyright 2000.  
  Figures were selected by an automated process.  

Literature references that cite this PDB file's key reference

  PubMed id Reference
18544344 A.Mesa, J.A.Somarelli, and R.J.Herrera (2008).
Spliceosomal immunophilins.
  FEBS Lett, 582, 2345-2351.  
17360628 M.D.Ohi, L.Ren, J.S.Wall, K.L.Gould, and T.Walz (2007).
Structural characterization of the fission yeast U5.U2/U6 spliceosome complex.
  Proc Natl Acad Sci U S A, 104, 3195-3200.  
16689644 H.Stark, and R.Lührmann (2006).
Cryo-electron microscopy of spliceosomal components.
  Annu Rev Biophys Biomol Struct, 35, 435-457.  
16134115 T.J.Pemberton, and J.E.Kay (2005).
The cyclophilin repertoire of the fission yeast Schizosaccharomyces pombe.
  Yeast, 22, 927-945.  
12907720 D.Ingelfinger, S.F.Göthel, M.A.Marahiel, U.Reidt, R.Ficner, R.Lührmann, and T.Achsel (2003).
Two protein-protein interaction sites on the spliceosome-associated human cyclophilin CypH.
  Nucleic Acids Res, 31, 4791-4796.  
11823439 D.S.Horowitz, E.J.Lee, S.A.Mabon, and T.Misteli (2002).
A cyclophilin functions in pre-mRNA splicing.
  EMBO J, 21, 470-480.  
11343899 C.L.Will, and R.Lührmann (2001).
Spliceosomal UsnRNP biogenesis, structure and function.
  Curr Opin Cell Biol, 13, 290-301.  
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