Elements · ← K Potassium · Sc Scandium →
Calcium signals inside cells, and fluorescent calcium indicators let scientists watch cells work.
| Symbol | Ca |
|---|---|
| Atomic number | 20 |
| Standard atomic weight | 40.08 |
| Group | 2 |
| Period | 4 |
| Block | s-block |
| Category | Alkaline earth metal |
| Standard state | Solid |
| Discovered | Ancient |
Source: PubChem, Calcium (periodic table data, retrieved 2026-10-19). Group and period follow the standard 18-column periodic table.
Nakai, Ohkura and Imoto built G-CaMP, a calcium probe made from a single green fluorescent protein, which binds Ca2+ with an apparent Kd of 235 nM and showed large fluorescence changes in cultured cells.
Built / tested: G-CaMP
As reported in: Nakai, Ohkura, Imoto (2001). A high signal-to-noise Ca2+ probe composed of a single green fluorescent protein. Nature Biotechnology. doi:10.1038/84397
Abstract only
Grynkiewicz, Poenie and Tsien made a new family of fluorescent Ca2+ indicators that were up to 30 times brighter than the earlier dye quin2 and change wavelength, not just brightness, when they bind calcium.
As reported in: Grynkiewicz, Poenie, Tsien (1985). A new generation of Ca2+ indicators with greatly improved fluorescence properties.. Journal of Biological Chemistry. doi:10.1016/s0021-9258(19)83641-4
Found by name, common compounds and chemical formulas in each entry.
Search Google Patents for calcium in biological and medical uses: all patents · recent applications (2022+)
A patent is a legal claim, not proof that something works. See the Patents page.