Figure 7: Conceptual model of the coccolith calcium pathway.
From: A vacuole-like compartment concentrates a disordered calcium phase in a key coccolithophorid alga
Ca accumulation and calcite precipitation are spatially and temporally separated. Calcium uptake into cells involves Ca transporter. The Ca ions are concentrated by polyphosphates into a disordered phase in a compartment distinct from the coccolith vesicle–reticular body system. The disordered Ca phase is a dynamic reservoir, concentrating and dispatching Ca ions. The released Ca ions are possibly transferred into the coccolith vesicle–reticular body system by Ca transporter and/or passive diffusion driven by a high-concentration gradient in free Ca ions. Inside the coccolith vesicle the calcium is precipitated as calcite.
