Discovery of the 'porosome'; the universal secretory machinery in cells.
The release of neurotransmitters at the nerve terminal for neurotransmission, release of insulin from beta-cells of the endocrine pancreas for regulating blood glucose levels, the release of growth hormone from GH cells of the pituitary gland to regulate body growth, or the expulsion of zymogen from exocrine pancreas to digest food, are only a few examples of key physiological processes made possible by cell secretion. It comes as no surprise that defects in cell secretion are the cause for numerous diseases, and have been under intense investigation for over half century. Only in the last decade, the molecular machinery and mechanism of cell secretion has become clear. Cell secretion involves the docking and transient fusion of membrane-bound secretory vesicles at the base of plasma membrane structures called porosomes, and the regulated expulsion of intravesicular contents to the outside, by vesicle swelling. The discovery of the porosome in live cells, its morphology and dynamics at nanometer resolution and in real time, its isolation, its composition, and its structural and functional reconstitution in lipid membrane, are complete. The molecular mechanism of secretory vesicle fusion at the base of porosomes, and the regulated expulsion of intravesicular contents during cell secretion, are also resolved. In this minireview, the monumental discovery of the porosome, a new cellular structure at the cell plasma membrane, is briefly discussed.
Section of Physiology, Department of Animal Science, College of Agriculture & Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 2356 Kildee Hall, Ames, IA 50011-3150, USA. llanders@iastate.edu
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D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation; D016384:Consensus Sequence; D008239:Lysine / Q000737:chemistry; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism*; D064326:MEF2 Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D018006:Myogenic Regulatory Factors / Q000235:genetics* / Q000378:metabolism*; D050828:Protein Inhibitors of Activated STAT / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; C578035:MEF2A protein, human; D018006:Myogenic Regulatory Factors; D050828:Protein Inhibitors of Activated STAT; D025842:SUMO-1 Protein; D044767:Ubiquitin-Protein Ligases; D008239:Lysine