4BM5: Chloroplast Inner Membrane Protein Tic110

Tic110 is a major component of the chloroplast protein import translocon. Two functions with mutually exclusive structures have been proposed for Tic110: a protein-conducting channel with six transmembrane domains and a scaffold with two N-terminal transmembrane domains followed by a large soluble domain for binding transit peptides and other stromal translocon components. To investigate the structure of Tic110, Tic110 from Cyanidioschyzon merolae (CmTic110) was characterized. We constructed three fragments, CmTic110A , CmTic110B and CmTic110C , with increasing N-terminal truncations, to perform small-angle X-ray scattering (SAXS) and X-ray crystallography analyses and Dali structural comparison. Here we report the molecular envelope of CmTic110B and CmTic110C determined by SAXS, and the crystal structure of CmTic110C at 4.2 A. Our data indicate that the C-terminal half of CmTic110 possesses a rod-shaped helix-repeat structure that is too flattened and elongated to be a channel. The structure is most similar to the HEAT-repeat motif that functions as scaffolds for protein-protein interactions.
PDB ID: 4BM5Download
MMDB ID: 110833
PDB Deposition Date: 2013/5/6
Updated in MMDB: 2013/09
Experimental Method:
x-ray diffraction
Resolution: 4.2  Å
Source Organism:
Similar Structures:
Biological Unit for 4BM5: monomeric; determined by author and by software (PISA)
Molecular Components in 4BM5
Label Count Molecule
Protein (1 molecule)
Similar to Chloroplast Inner Membrane Protein Tic110
Molecule annotation
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Citing MMDB