title: MARCH-III Is a novel component of endosomes with properties similar to those of MARCH-II.
abstract: MARCH comprises a recently identified family of transmembrane RING-finger proteins which is implicated in diverse biological functions, such as immune regulation, protein quality control, and membrane trafficking. We previously identified MARCH-II, as a binding partner of syntaxin 6, which plays a role in endosomal protein transport. In this paper, we describe the cloning and characterization of MARCH-III which is the closest homolog of MARCH-II. It is broadly expressed at relatively high levels in spleen, colon, and lung. An immunofluorescence study of HeLa cells demonstrated that MARCH-III is present in peripheral vesicles partially colocalized with transferrin receptor. Overexpression of MARCH-III resulted in the redistribution of TGN46 and strong inhibition of transferrin uptake. Immunoprecipitation studies revealed that MARCH-III is associated with syntaxin 6 and MARCH-II. Mutational analyses revealed that the PDZ-binding motif and RING finger are essential for the subcellular localization of MARCH-III and the inhibitory effect on transferrin uptake. The location, associated molecules, and effects of overexpression suggest that MARCH-III is involved in the regulation of vesicular trafficking in endosomes.
authors.affiliation: Department of Biological Sciences, Tokyo Institute of Technology, 4259-B-19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Fukuda
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakamura
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Hirose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers; D011992:Endosomes / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D044767:Ubiquitin-Protein Ligases
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D008565:Membrane Proteins; C502926:MARCHF2 protein, human; D044767:Ubiquitin-Protein Ligases