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Analyses of the Recycling Receptor, FcRn, in Live Cells Reveal Novel Pathways for Lysosomal Delivery
Author(s) -
Gan Zhuo,
Ram Sripad,
Vaccaro Carlos,
Ober Raimund J.,
Ward E. Sally
Publication year - 2009
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.1600-0854.2009.00887.x
Subject(s) - endosome , microbiology and biotechnology , endocytosis , biology , endocytic cycle , lysosome , receptor , vesicle , vesicular transport proteins , cytosol , membrane , biochemistry , intracellular , enzyme , vacuolar protein sorting
Lysosomes play a central role in the degradation of proteins and other macromolecules. The mechanisms by which receptors are transferred to lysosomes for constitutive degradation are poorly understood. We have analyzed the processes that lead to the lysosomal delivery of the Fc receptor, FcRn. These studies provide support for a novel pathway for receptor delivery. Specifically, unlike other receptors that enter intraluminal vesicles in late endosomes, FcRn is transferred from the limiting membrane of such endosomes to lysosomes, and is rapidly internalized into the lysosomal lumen. By contrast, LAMP‐1 persists on the limiting membrane. Receptor transfer is mediated by tubular extensions from late endosomes to lysosomes, or by interactions of the two participating organelles in kiss‐and‐linger‐like processes, whereas full fusion is rarely observed. The persistence of FcRn on the late endosomal limiting membrane, together with selective transfer to lysosomes, allows this receptor to undergo recycling or degradation. Consequently, late endosomes have functional plasticity, consistent with the presence of the Rab5 GTPase in discrete domains on these compartments.