Calcium-regulated, actin-modulating protein that binds to the plus (or barbed) ends of actin monomers or filaments, preventing monomer exchange (end-blocking or capping). It can promote the assembly of monomers into filaments (nucleation) as well as sever filaments already formed. Plays a role in ciliogenesis (By similarity). Binds to actin and to fibronectin. A cytoplasmic form may also exist. Highly expressed in homogene cells of the basilar papilla. Also detected in subcutaneous layer of the skin. Comprises six structurally related domains, in a calcium-free environment, pack together to form a compact globular structure in which the putative actin-binding sequences are not sufficiently exposed to enable binding to occur. Binding calcium may release the connections that join the N- and C-terminal halves of gelsolin, enabling each half to bind actin relatively independently. The severing and capping properties of gelsolin are inhibited by binding polyphosphoinositides. Belongs to the villin/gelsolin family.