title: Visualization of the post-Golgi trafficking of multiphoton photoactivated transferrin receptors.
abstract: Newly synthesized membrane proteins are sorted in the trans-Golgi network (TGN) on the basis of sorting signals carried in their cytoplasmic domains and delivered to their final destinations in the secretory and endocytic pathways. Although previous studies have suggested the involvement of early endosomes in the biosynthetic pathway of transmembrane proteins, the precise trafficking routes followed by the newly synthesized plasma membrane proteins, such as transferrin receptors (TfRs), after exit from the TGN remain unclear. In this report, first, we demonstrated the advantages of photoactivating PA-GFP, a variant of the Aequorea victoria green fluorescent protein (GFP), with multiphoton laser light rather than single-photon laser light, in terms of photoactivation efficiency and spatial resolution. We then applied the multiphoton photoactivation technique to selectively photoactivate the TfR tagged with PA-GFP (PA-GFP-TfR) at the TGN, and monitored the movement of the photoactivated PA-GFP-TfR in live cells. We observed that the PA-GFP-TfR photoactivated at the TGN are transported to the Tfn(+)EEA1(+) endosomal compartments after exiting the TGN. These data support the notion that early endosomes can serve as a sorting station for not only internalized plasma membrane proteins in the endocytic pathway but also newly synthesized membrane proteins in the post-Golgi secretory pathway.
authors.affiliation: Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology, RIKEN.
authors.forename: Hong
authors.initials: H
authors.lastname: Luo
authors.forename: Fubito
authors.initials: F
authors.lastname: Nakatsu
authors.forename: Akiko
authors.initials: A
authors.lastname: Furuno
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kato
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohno
mesh_terms: D001324:Autoantigens / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D000077614:Golgi Matrix Proteins; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D007834:Lasers; D008027:Light; D008164:Luminescent Proteins; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D016253:Microscopy, Immunoelectron; D010777:Photochemistry / Q000379:methods* / Q000639:trends; D021381:Protein Transport / Q000502:physiology; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D013194:Staining and Labeling / Q000295:instrumentation / Q000379:methods; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure; D000097573:Red Fluorescent Protein
chemical_list: D001324:Autoantigens; D000077614:Golgi Matrix Proteins; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; D000097573:Red Fluorescent Protein; C450721:Golgi complex autoantigen, 97-kDa