Adseverin is a Ca(2+)-dependent actin filament-severing protein that is presumed to have a regulatory function in exocytosis by affecting the organization of the microfilament network underneath the plasma membrane. As the first step to investigate whether adseverin has the expected function in vivo, we have cloned a cDNA for bovine adseverin. Analysis of the nucleotide sequence revealed the following points. 1) Adseverin consisted of 715 amino acid residues, and its predicted molecular mass was 80.5 kDa. 2) Adseverin belonged to the gelsolin family of proteins, which consists of six homologous segments. 3) Adseverin had two putative polyphosphoinositide binding sequences, very similar to but distinct from those in gelsolin. Adseverin was produced in Escherichia coli and purified to homogeneity. The adseverin reacted with adseverin-specific antibody and showed Ca(2+)-dependent actin filament severing activity like authentic adseverin. In situ hybridization demonstrated that adseverin mRNA was differentially expressed in the bovine adrenal gland; it was expressed in the adrenal medulla but not in most parts of the adrenal cortex, although both have a secretory function. The observation strongly suggested that adseverin is not involved in secretory processes in general but is specifically involved in exocytosis.