Intracellular trafficking of prohormones and proneuropeptides: Cell type-specific sorting and targeting

Abstract

Hormones and neuropeptides are usually synthesized as large precursor molecules which must undergo a series of post-translational modifications before they are released from secretory vesicles after stimulation by specific secretagogues. The classical vectorial transport of precursors and mature peptide products from the endoplasmic reticulum (ER) to their site of release has been the subject of intensive studies during the past 25 years, but there are a number of unresolved issues which still challenge cell biologists. The main issues are: (i) the molecular mechanisms underlying targeting and sorting of prohormones within the eukaryotic secretory pathway; (ii) further identification and intracellular site of action of post-translational processing enzymes; (iii) tissue-specific processing of hormone and neuropeptide precursors; and (iv) molecular mechanisms underlying intracellular transport ofl hormone and neuropeptide precursors and their cleavage products to alternative intracellular compartments besides the secretory pathway.