Calcium overlay assay

The calcium overlay assay (Maruyama etal., 1984) as described here is essentially a specific application of a general metal ion binding assay (Aoki et al., 1986). The method has been used to identify calcium-binding proteins that contain EF hands (Hoffmann et al., 1993) as well as other types of calcium-binding proteins (Son et al., 1993) transferred to nitrocellulose from either one- or two dimensional gels (see article by Julio E. Celis, Jette B. Lauridsen, and Bodil Basse). The procedure can be performed at room temperature within 24 hr and can detect as little as 20 pmole of calcium binding sites. 

---