The gene encoding the calcium binding protein calcyclin is expressed at sites of exocytosis in the mouse.

Calcyclin is a member of the S100 family of calcium binding proteins. We have found by in situ hybridization that calcyclin transcripts are restricted to specific cell types within a limited number of mouse organs. High levels of expression in the epithelia lining the gastrointestinal, respiratory and urinary tracts, and specific localization of the transcripts to the goblet cells in the small intestine, lead us to suggest a role for calcyclin in the process of mucus secretion. In addition, calcyclin expression was detected in the corpus luteum, placenta and nerves within the gut wall, which are all sites of regulated exocytosis. We propose that this S100-like protein may be part of a calcium signalling pathway utilized in the secretion of various products by different cell types.