4P5W

Structure of the N- and C-terminal domain fusion of the human mitochondrial aspartate/glutamate carrier Citrin in the calcium-bound state

Summary for 4P5W

• Entry DOI: 10.2210/pdb4p5w/pdb
• Descriptor: Calcium-binding mitochondrial carrier protein Aralar2,Calcium-binding mitochondrial carrier protein Aralar2, CALCIUM ION (3 entities in total)
• Functional Keywords: transport protein
• Biological source: Homo sapiens (Human); More
• Cellular location: Mitochondrion inner membrane ; Multi-pass membrane protein : Q9UJS0
• Total number of polymer chains: 2
• Total formula weight: 92040.34

Authors

Thangaratnarajah, C.,Ruprecht, J.J.,Kunji, E.R.S. (deposition date: 2014-03-20, release date: 2014-11-26, Last modification date: 2024-05-08)

Primary citation

Thangaratnarajah, C.,Ruprecht, J.J.,Kunji, E.R.
Calcium-induced conformational changes of the regulatory domain of human mitochondrial aspartate/glutamate carriers.
Nat Commun, 5:5491-5491, 2014

PubMed Abstract: The transport activity of human mitochondrial aspartate/glutamate carriers is central to the malate-aspartate shuttle, urea cycle, gluconeogenesis and myelin synthesis. They have a unique three-domain structure, comprising a calcium-regulated N-terminal domain with eight EF-hands, a mitochondrial carrier domain, and a C-terminal domain. Here we present the calcium-bound and calcium-free structures of the N- and C-terminal domains, elucidating the mechanism of calcium regulation. Unexpectedly, EF-hands 4-8 are involved in dimerization of the carrier and form a static unit, whereas EF-hands 1-3 form a calcium-responsive mobile unit. On calcium binding, an amphipathic helix of the C-terminal domain binds to the N-terminal domain, opening a vestibule. In the absence of calcium, the mobile unit closes the vestibule. Opening and closing of the vestibule might regulate access of substrates to the carrier domain, which is involved in their transport. These structures provide a framework for understanding cases of the mitochondrial disease citrin deficiency.

PubMed: 25410934
DOI: 10.1038/ncomms6491

Experimental method

X-RAY DIFFRACTION (2.4 Å)