3UOM

Ca2+ complex of Human skeletal calsequestrin

Summary for 3UOM

• Entry DOI: 10.2210/pdb3uom/pdb
• Related: 3US3
• Descriptor: Calsequestrin-1, (4R)-2-METHYLPENTANE-2,4-DIOL, (4S)-2-METHYL-2,4-PENTANEDIOL, ... (5 entities in total)
• Functional Keywords: thioredoxin-like fold, calcium binding, sarcoplasmic reticulum, calcium-binding protein
• Biological source: Homo sapiens (human)
• Cellular location: Sarcoplasmic reticulum lumen: P31415
• Total number of polymer chains: 6
• Total formula weight: 258745.48

Authors

Sanchez, E.J.,Lewis, K.M.,Danna, B.R.,Nissen, M.S.,Kang, C.H. (deposition date: 2011-11-16, release date: 2012-02-22, Last modification date: 2023-09-13)

Primary citation

Sanchez, E.J.,Lewis, K.M.,Danna, B.R.,Kang, C.
High-capacity Ca2+ Binding of Human Skeletal Calsequestrin.
J.Biol.Chem., 287:11592-11601, 2012

PubMed Abstract: Calsequestrin, the major calcium storage protein in both cardiac and skeletal muscle, binds large amounts of Ca(2+) in the sarcoplasmic reticulum and releases them during muscle contraction. For the first time, the crystal structures of Ca(2+) complexes for both human (hCASQ1) and rabbit (rCASQ1) skeletal calsequestrin were determined, clearly defining their Ca(2+) sequestration capabilities through resolution of high- and low-affinity Ca(2+)-binding sites. rCASQ1 crystallized in low CaCl(2) buffer reveals three high-affinity Ca(2+) sites with trigonal bipyramidal, octahedral, and pentagonal bipyramidal coordination geometries, along with three low-affinity Ca(2+) sites. hCASQ1 crystallized in high CaCl(2) shows 15 Ca(2+) ions, including the six Ca(2+) ions in rCASQ1. Most of the low-affinity sites, some of which are μ-carboxylate-bridged, are established by the rotation of dimer interfaces, indicating cooperative Ca(2+) binding that is consistent with our atomic absorption spectroscopic data. On the basis of these findings, we propose a mechanism for the observed in vitro and in vivo dynamic high-capacity and low-affinity Ca(2+)-binding activity of calsequestrin.

PubMed: 22337878
DOI: 10.1074/jbc.M111.335075

Experimental method

X-RAY DIFFRACTION (2.02 Å)