5DSE

Crystal Structure of the TTC7B/Hyccin Complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.9 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.212 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The leukodystrophy protein FAM126A (hyccin) regulates PtdIns(4)P synthesis at the plasma membrane.

Baskin, J.M.Wu, X.Christiano, R.Oh, M.S.Schauder, C.M.Gazzerro, E.Messa, M.Baldassari, S.Assereto, S.Biancheri, R.Zara, F.Minetti, C.Raimondi, A.Simons, M.Walther, T.C.Reinisch, K.M.De Camilli, P.

(2016) Nat.Cell Biol. 18: 132-138

  • DOI: 10.1038/ncb3271

  • PubMed Abstract: 
  • Genetic defects in myelin formation and maintenance cause leukodystrophies, a group of white matter diseases whose mechanistic underpinnings are poorly understood. Hypomyelination and congenital cataract (HCC), one of these disorders, is caused by mu ...

    Genetic defects in myelin formation and maintenance cause leukodystrophies, a group of white matter diseases whose mechanistic underpinnings are poorly understood. Hypomyelination and congenital cataract (HCC), one of these disorders, is caused by mutations in FAM126A, a gene of unknown function. We show that FAM126A, also known as hyccin, regulates the synthesis of phosphatidylinositol 4-phosphate (PtdIns(4)P), a determinant of plasma membrane identity. HCC patient fibroblasts exhibit reduced PtdIns(4)P levels. FAM126A is an intrinsic component of the plasma membrane phosphatidylinositol 4-kinase complex that comprises PI4KIIIα and its adaptors TTC7 and EFR3 (refs 5,7). A FAM126A-TTC7 co-crystal structure reveals an all-α-helical heterodimer with a large protein-protein interface and a conserved surface that may mediate binding to PI4KIIIα. Absence of FAM126A, the predominant FAM126 isoform in oligodendrocytes, destabilizes the PI4KIIIα complex in mouse brain and patient fibroblasts. We propose that HCC pathogenesis involves defects in PtdIns(4)P production in oligodendrocytes, whose specialized function requires massive plasma membrane expansion and thus generation of PtdIns(4)P and downstream phosphoinositides. Our results point to a role for FAM126A in supporting myelination, an important process in development and also following acute exacerbations in multiple sclerosis.


    Organizational Affiliation

    Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut  06510, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Tetratricopeptide repeat protein 7B
A, C
837Homo sapiensMutation(s): 0 
Gene Names: TTC7B (TTC7L1)
Find proteins for Q86TV6 (Homo sapiens)
Go to Gene View: TTC7B
Go to UniProtKB:  Q86TV6
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Hyccin
B, D
312Homo sapiensMutation(s): 0 
Gene Names: FAM126A (DRCTNNB1A)
Find proteins for Q9BYI3 (Homo sapiens)
Go to Gene View: FAM126A
Go to UniProtKB:  Q9BYI3
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.9 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.212 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 71.779α = 90.00
b = 168.068β = 90.00
c = 239.671γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement
SHELXphasing
Cootmodel building
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2015-12-02
    Type: Initial release
  • Version 1.1: 2016-01-13
    Type: Database references
  • Version 1.2: 2017-11-22
    Type: Derived calculations, Refinement description