Non-EF-Hand Calcium Binding Proteins
Several non-EF-hand calcium-binding proteins have been studied in the past few years with regard to their participation in normal physiological processes and their apparent ability to modulate biological behaviour of cells (see Table 2). Of these, annexins, gelsolin, calreticulin, and osteocalcin have been extensively investigated. Although they are grouped together here as non-EF-hand CBPs, the pathways of their approach to the modulation of cell physiology and function are distinctively different. Annexins are calcium-dependent membrane binding proteins that participate in membranerelated processes of fusion, adhesion, exocytosis, and the remodelling of the plasma membrane. Calreticulin also subserves a membrane-associated function (e.g., the intracellular storage of calcium). Osteocalcin is an extracellular matrix protein and is involved in bone metabolism. It is apparently also signiﬁcantly implicated in invasive behaviour of cancers, their proliferation, and osteotropic metastasis. In contrast, gelsolin activity is mainly targeted on the cytoskeletal dynamics.