title: GFP-like proteins stably accumulate in lysosomes.
abstract: Green fluorescent protein (GFP) from the jellyfish Aequorea victoria, its GFP variants (Aequorea GFPs), and more recently the novel GFP-like proteins from Anthozoa have greatly advanced our technologies for fluorescently labeling cells, organelles, and proteins. It has been shown, however, that some GFP-like proteins have a tendency to oligomerize and aggregate. Transfection of GFP-like proteins into cultured mammalian cells results in bright punctate structures, which are thought to be cytosolic protein aggregates. In this study, we demonstrate that these structures are not cytosolic aggregates but lysosomes that have accumulated the GFP-like proteins. Our biochemical and immunocytochemical experiments have revealed that certain GFP-like proteins expressed in the cytosol enter lysosomes possibly by an autophagy-related mechanism, but retain their fluorescence because of resistance not only to acidity but also to lysosomal proteases.
authors.affiliation: Laboratory for Cell Function Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Katayama
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Noboru
authors.initials: N
authors.lastname: Mizushima
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Yoshimori
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyawaki
mesh_terms: D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008247:Lysosomes / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D010447:Peptide Hydrolases / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D011506:Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010447:Peptide Hydrolases