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Calcium-binding proteins

The role of Ca2+ as a key and pivotal second messenger in cells depends largely on a wide number of heterogeneous so-called calcium binding proteins (CBP), which have the ability to bind this ion in specific domains. CBP contribute to the control of Ca2+ concentration in the cytosol and participate in numerous cellular functions by acting as Ca2+ transporters across cell membranes or as Ca2+-modulated sensors, i.e., decoding Ca2+ signals. In this chapter we review the main Ca2+-modulated CBP, starting with those intracellular CBP that contain the structural EF-hand domain: parvalbumin, calmodulin, S100 proteins and calcineurin. Then, we address intracellular CBP lacking the EF-hand domain: CBP within intracellular Ca2+ stores (paying special attention to calreticulin and calsequestrin), annexins and proteins that contain a C2 domain, such as protein kinase C (PKC) or synaptotagmin. Finally, extracellular CBP have been classified in six groups, according to their Ca2+ binding structures: (i) EF-hand domains; (ii) EGF-like domains; (iii) γ-carboxyl glutamic acid (GLA)-rich domains; (iv) cadherin domains; (v) Ca2+-dependent (C)-type lectin-like domains; (vi) Ca2+-binding pockets of family C G-protein-coupled receptors. [from: Yáñez M., Gil-Longo J., Campos-Toimil M. (2012) Calcium Binding Proteins. In: Islam M. (eds) Calcium Signaling. Advances in Experimental Medicine and Biology, vol 740. Springer, Dordrecht]

Anti Parvalbumin Alpha pAb (Rabbit, Affinity Purified) CAC-ACC-PA001 RAB HU RT
Anti Protein S100-A1 (S100 Alpha) pAb (Rabbit, Affinity Purified) CAC-ACC-PA002 RAB HU MS RT BOV POR
Anti Calbindin (D-28K) pAb (Rabbit, Affinity Purified) CAC-ACC-PA003 RAB HU MS RT
Product name Anti Parvalbumin Alpha pAb (Rabbit, Affinity Purified)
Cat No CAC-ACC-PA001
Description Parvalbumin (PV) is a calcium binding protein expressed in specific muscle fibers and fast-firing neurons. PV consists of a single, unbranched chain of linked amino acids and belongs to a larger group of EF hand proteins. Studies have demonstrated that parvalbumin acts in the decay of calcium in the contraction/relaxation cycle of fast twitch muscles. This data has shown a positive correlation between the rate of relaxation and the concentration of parvalbumin. Parvalbumin is also expressed in a specific population of GABAergic interneurons which are thought to play a role in maintaining the balance between excitation and inhibition in the cortex as well as the hippocampus. In amyotrophic lateral sclerosis (ALS) patents, parvalbumin immunoreactivity is specifically absent from neuron populations lost early in ALS.

References:
Inaguma Y, Kurobe N, Shinohara H, Kato K. (1991) Sensitive immunoassay for rat parvalbumin: tissue distribution and developmental changes. Biochim Biophys Acta. 1075:68-74.
Host RAB
Species specificity HU RT
 
Product name Anti Protein S100-A1 (S100 Alpha) pAb (Rabbit, Affinity Purified)
Cat No CAC-ACC-PA002
Description The S100 protein is a low-molecular-weight, acidic and calcium-binding protein that in functional form exists as a dimer. S100 has two subunits: S100-alpha (94 aa; human chromosome 1) and S100-beta (92 aa; human chromosome 21) that assemble as either homodimers (alpha-alpha known as S-100a(0) or beta-beta known as S-100b) or as heterodimers (known as S-100a) of ~21 kDa. S100-alpha and -beta chains show ~58% sequence identity and are both highly conserved. S100-alpha was originally believed to be localized to the CNS but studies have shown it to be found in numerous tissues including cardiac, skeletal and vascular smooth muscle cells.

References:
Kato K, Haimoto H, Ariyoshi Y, Horisawa M, Washida H, Kimura S. (1985) High levels of S-100a0 (alpha alpha) protein in tumor tissues and in sera of patients with renal cell carcinoma. Jpn J Cancer Res. 76:856-62.
Host RAB
Species specificity HU MS RT BOV POR
 
Product name Anti Calbindin (D-28K) pAb (Rabbit, Affinity Purified)
Cat No CAC-ACC-PA003
Description Vitamin D-dependent 28 kDa calcium-binding protein (calbindin D 28k or CB) is a member of the calmodulin superfamily of calcium binding proteins discovered in 1966 by Wasserman and Taylor. The protein has a distinct distribution in the brain and sensory system and is abundant in specific neuronal cell types. Calbindin D-28k constitutes as much as 0.1-1.5 % of the total soluble protein in brain and it may be present at intracellular concentrations up to 1 mM. Several recent studies have shown that calbindin D can protect cells from degeneration and ischemic injury under extracellular stress. This is demonstrated in the brain of Alzheimer disease patients where cells containing calbindin D have a considerably lower burden of plaques and tangles than those lacking this 28 kDa protein.

References:
Zhu YY, Takashi M, Miyake K, Kato K. (1991) Sensitive enzyme immunoassay for human 28 kDa calbindin-D. Clin Chim Acta. 201:183-92.
Host RAB
Species specificity HU MS RT