Proteolytic processing and Ca2+-binding activity of dense-core vesicle polypeptides in Tetrahymena.

ABSTRACT: Formation and discharge of dense-core secretory vesicles depend on controlled rearrangement of the core proteins during their assembly and dispersal. The ciliate Tetrahymena thermophila offers a simple system in which the mechanisms may be studied. Here we show that most of the core consists of a set of polypeptides derived proteolytically from five precursors. These share little overall amino acid identity but are nonetheless predicted to have structural similarity. In addition, sites of proteolytic processing are notably conserved and suggest that specific endoproteases as well as carboxypeptidase are involved in core maturation. In vitro binding studies and sequence analysis suggest that the polypeptides bind calcium in vivo. Core assembly and postexocytic dispersal are compartment-spec

SUBMITTER: Verbsky JW 

PROVIDER: S-EPMC25279 | biostudies-literature | 1998 Feb

REPOSITORIES: biostudies-literature