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Novel Secretory Vesicle Proteins Essential for Membrane Fusion Display Extracellular‐Matrix Domains
Author(s) -
Froissard Marine,
Keller AnneMarie,
Dedieu JeanClaude,
Cohen Jean
Publication year - 2004
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2004.00194.x
Subject(s) - biology , microbiology and biotechnology , secretory pathway , protein targeting , transmembrane protein , exocytosis , snap25 , lipid bilayer fusion , membrane protein , secretory protein , vesicle fusion , secretory vesicle , fusion protein , vesicle , transport protein , secretion , golgi apparatus , biochemistry , receptor , membrane , synaptic vesicle , endoplasmic reticulum , gene , recombinant dna
Exocytotic mutants can be obtained in Paramecium that affect the organization of the fusion machinery, visible by electron microscopy. The site of action of the genes in the plasma membrane, cytosol or secretory compartment can easily be determined in such mutants. Functional complementation cloning of exocytotic mutants specifically affected in the secretory compartment, nd2‐1 and nd169‐1, reported here, and the previously studied nd7‐1, led to the discovery of a set of novel proteins that display PSI and EGF domains, normally found in extracellular matrix proteins and involved in transmembrane signaling. The structure of one of these proteins, Nd2p, and of the product of a paralog found in the genome Nd22p, corresponds to that of type I membrane receptors, generally involved in protein and vesicle sorting. Our characterization suggests that the proteins we have identified are required to indicate the presence of a mature secretory vesicle to the plasma membrane, to prepare the machinery for fusion. We propose to name this novel subclass of receptors VEMIF, for Vesicular Extracellular‐Matrix‐like proteins Involved in preparing membrane Fusion.