title: Transmembrane 6 superfamily 1 (Tm6sf1) is a novel lysosomal transmembrane protein.
abstract: The lysosome is a membrane-bound organelle involved in the turnover of various intracellular and extracellular macromolecules. These are degraded by acidic hydrolases in the lumen of lysosome. The lysosomal membrane is important not only in retaining the acidic hydrolases to protect cells against cytosolic proteolysis, but it also facilitates protein trafficking though organelle fusion. In this study, we report on a novel lysosomal membrane protein transmembrane 6 superfamily 1 (Tm6sf1). Expression of Tm6sf1-DsRed fusion proteins in HEK293A cells displayed punctate or ringlike vesicles, which colocalized with conventional lysosome markers including LAMP1/2, RAB7, and Rnf167. Using fluorescence time-lapse live cell imaging, we demonstrated the fusion of Tm6sf1 vesicles with lysosomes and the integration of Tm6sf1 into the lysosomal membrane. We also examined the expression of Tm6sf1 in mouse tissues and found immunopositive signals in major organs such as the cerebellum, kidney, and intestine. These data suggest that Tm6sf1 is a widely expressed lysosomal transmembrane protein and can be used as a novel marker of lysosome.
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Wing Yip
authors.initials: WY
authors.lastname: Tam
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
authors.forename: Kin Ming
authors.initials: KM
authors.lastname: Kwan
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D006801:Humans; D007150:Immunohistochemistry; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D021381:Protein Transport / Q000502:physiology; D044767:Ubiquitin-Protein Ligases; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
chemical_list: D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D008565:Membrane Proteins; C419194:TM6SF1 protein, human; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; C000716465:rab7 GTP-binding proteins, mouse; D044767:Ubiquitin-Protein Ligases; D020691:rab GTP-Binding Proteins