Calbindins - what do they do?
Our cells contain numerous proteins thought to bind calcium as their primary role. Many of these calcium-binding proteins play pivotal roles in cell signalling, regulation and structure, making them attractive targets for therapeutic intervention in multiple diseases including cancer and neurodegeneration. However, for such applications to be fully effective, better understanding is needed about the functions of these calcium-binding proteins at individual and collective levels. Calbindins comprise three types of calcium-binding protein (calbindin-28kDa, calbindin-9kDa, calretinin) that have long been regarded as mobile calcium buffers in the cytosol and consequently are widely investigated as potential targets in calcium transport and neurodegeneration. Our investigations have contradicted this view and instead pointed to calbindins having a role that involves interactions with other proteins. These findings, which lead us to contemplate an alternative role in cell signalling, hold fundamental significance for medical targeting of calbindins. These outcomes also necessitate reconsideration of the mechanisms used in transepithelial calcium transport (see Calcium Handling project).
Dr Jon Mangum, Project co-leader
- Hubbard MJ, McHugh NJ, Mangum JE. Exclusion of all three calbindins from a calcium-ferry role in rat enamel cells. Eur J Oral Sci 2011; 119 (Suppl. 1), 112-119 (PMID: 22243236)
- Turnbull CI, Looi K, Mangum JE, Meyer M, Sayer RJ, Hubbard MJ. Calbindin-independence of calcium transport in developing teeth contradicts the calcium-ferry dogma. J Biol Chem 2004; 279: 55850-55854. (PMID: 15494408)
- Sayer RJ, Turnbull CI, Hubbard MJ. Calbindin28kDa is specifically associated with extra-nuclear constituents of the dense particulate fraction. Cell Tiss Res. 2000; 302:171-180. (PMID: 11131128)
- Hubbard MJ, McHugh NJ. Calbindin28kDa and calbindin30kDa (calretinin) are substantially localised in the particulate fraction of rat brain. FEBS Lett 1995; 374: 333-337. (PMID: 7589565)
- Hubbard, M.J. Calbindin28kDa and calmodulin are hyperabundant in rat dental enamel cells. Identification of the protein phosphatase calcineurin as a principal calmodulin target and of a secretion-related role for calbindin28k Da. Eur. J. Biochem 1995; 230: 68-79. (PMID: 7601126)
- Hubbard M.J. and Carne A. Differential feeding-related regulation of ubiquitin and calbindin9kDa in rat duodenum. Biochim. Biophys. Acta 1994; 1200: 191-6. (PMID: 8031840)
- Hubbard, M.J. (1993) Rapid purification and direct microassay of calbindin9kDa utilizing its solubility in perchloric acid.
Biochem. J 1993; 293: 223-7. (PMID: 8392333)
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