Homotypic Fusion of Immature Secretory Granules during Maturation in a Cell-free Assay

• DOI: 10.1083/jcb.143.7.1831
• Publication Date: 2002-07-26T16:45:41Z
• Authors: Sylvie Urbé; Lesley J. Page; Sharon A. Tooze
• Keywords: Furin; Male; 0301 basic medicine; Cell-Free System; Proteins; Cytoplasmic Granules; Membrane Fusion; PC12 Cells; Exocytosis; Rats; Rats, Sprague-Dawley; 03 medical and health sciences; Adenosine Triphosphate; Cytosol; Chromogranins; Animals; Female; Guanosine Triphosphate; Subtilisins; Rats, Wistar; Carrier Proteins; N-Ethylmaleimide-Sensitive Proteins

The biogenesis of secretory granules embodies several morphological and biochemical changes. In particular, in neuroendocrine cells maturation is characterized by an increase size which has been proposed to reflect homotypic fusion immature (ISGs). Here we describe assay that provides the first evidence for such a event allows us analyze its regulation. reconstitutes between one population ISGs containing [35S]sulfate-labeled substrate, secretogranin II (SgII), second prohormone convertase PC2. Both substrate enzyme are targeted exclusively ISGs. Fusion measured quantification cleavage product SgII produced With this show only occurs not MSGs, temperature dependent, requires ATP GTP cytosolic proteins. NSF (N-ethylmaleimide–sensitive protein) amongst proteins required, whereas could detect requirement p97. ability reconstitute ISG cell-free important advance towards identification molecules involved will our understanding process.