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8.A.88  The Calciquestrin (CAQS) Family 

Calsequestrins (CSR1 and CSR2) are high-capacity, moderate affinity, calcium-binding proteins that act as internal calcium stores in the lumin of the muscle sarcoplasmic reticulum (SR). Calcium ions are bound by clusters of acidic residues at the protein surface, often at the interface between subunits. The protein can bind around 80 Ca2+ ions. It regulates the release of lumenal Ca2+ via the ryanodine calcium release channel RYR1 (TC# 1.A.3.1.2) which plays an important role in triggering muscle contraction (Sanchez et al. 2012). CSR also negatively regulates store-operated Ca2+ entry (SOCE) activity (Zhang et al. 2016).

This family belongs to the: LysE Superfamily.

References associated with 8.A.88 family:

Chen, W. and M. Kudryashev. (2020). Structure of RyR1 in native membranes. EMBO Rep 21: e49891. 32147968
Guerra, C. and M. Molinari. (2020). Thioredoxin-Related Transmembrane Proteins: TMX1 and Little Brothers TMX2, TMX3, TMX4 and TMX5. Cells 9:. 32878123
Haugstetter, J., T. Blicher, and L. Ellgaard. (2005). Identification and characterization of a novel thioredoxin-related transmembrane protein of the endoplasmic reticulum. J. Biol. Chem. 280: 8371-8380. 15623505
Ihara, M., S. Furutani, S. Shigetou, S. Shimada, K. Niki, Y. Komori, M. Kamiya, W. Koizumi, L. Magara, M. Hikida, A. Noguchi, D. Okuhara, Y. Yoshinari, S. Kondo, H. Tanimoto, R. Niwa, D.B. Sattelle, and K. Matsuda. (2020). Cofactor-enabled functional expression of fruit fly, honeybee, and bumblebee nicotinic receptors reveals picomolar neonicotinoid actions. Proc. Natl. Acad. Sci. USA 117: 16283-16291. 32611810
Lee, S., Y. Shin, K. Kim, Y. Song, Y. Kim, and S.W. Kang. (2020). Protein Translocation Acquires Substrate Selectivity Through ER Stress-Induced Reassembly of Translocon Auxiliary Components. Cells 9:. 32102453
Sanchez, E.J., K.M. Lewis, B.R. Danna, and C. Kang. (2012). High-capacity Ca2+ binding of human skeletal calsequestrin. J. Biol. Chem. 287: 11592-11601. 22337878
Zhang, L., L. Wang, S. Li, J. Xue, and D. Luo. (2016). Calsequestrin-1 Regulates Store-Operated Ca2+ Entry by Inhibiting STIM1 Aggregation. Cell Physiol Biochem 38: 2183-2193. 27185316