| Abstract: | Protein secretion is conventionally viewed as taking place by either of two cellular routes, a regulated pathway, involving external stimuli and secretory granules, and a presumptive ‘constitutive’ pathway, which does not involve hormonal or neuronal stimuli or the production of secretory granules. The evidence reviewed here strongly suggests that there are post-synthesis rate-limiting steps for many proteins released by the ‘constitutive’ pathway and, hence, that regulation in some sense is involved here too. The nature of these rate-limiting determinants and events is discussed. |
