Stimulation of calmodulin by cadmium ion

✍ Scribed by Yasuhiro Suzuki; Sheng-Hao Chao; John R. Zysk; Wai Yiu Cheung

• Book ID: 104707014
• Publisher: Springer-Verlag
• Year: 1985
• Tongue: English
• Weight: 841 KB
• Volume: 57
• Category: Article
• ISSN: 0340-5761
• DOI: 10.1007/bf00290889

✦ Synopsis

Cd2+, a serious environmental pollutant in certain industrial regions, accumulates in mammalian tissues with a very slow turnover. Using various criteria, we studied the ability of Cd2+ to substitute for Ca2+ in calmodulin (CaM), a ubiquitous Ca2+-binding protein that mediates many of the Ca2+ effects. CaM bound Cd2+ with a Kd of 4.5 microM, presumably to the Ca2+-binding sites. Binding of Cd2+ allowed CaM to bind 2 moles chlorpromazine, or to form a complex with skeletal muscle troponin-I, troponin-T, or phosphodiesterase. Complex formation with phosphodiesterase led to its activation, which was observed even in the presence of glutathione or cysteine, agents known to chelate Cd2+. This raises the possibility that one manifestation of Cd2+ toxicity may be through its activation of CaM, thus upsetting its normal regulation by a cellular flux of Ca2+.