title: The tyrosinase tail mediates sorting to the lysosomal compartment in MDCK cells via a di-leucine and a tyrosine-based signal.
abstract: Tyrosinase is a type I membrane protein found in melanosomes, which are lysosomal-like organelles and specific for pigment cells. A mutation of mouse tyrosinase, platinum (cp), leads to truncation of tyrosinase's cytosolic tail, and results in misrouting to the cell periphery. In this study, we expressed chimeras of wild-type and mutant cytosolic tails of mouse tyrosinase fused to rat lysosome-associated membrane protein-1 luminal and transmembrane domain to study sorting of tyrosinase in Madin-Darby canine kidney cells. The study shows that the mouse tyrosinase cytosolic tail is necessary and sufficient to mediate sorting of a heterologous type I membrane protein to compartments of the lysosomal lineage. Whereas deletions of 7 or 10 C-terminal amino acids of the tail still result in sorting to lysosomes, a deletion mutant corresponding to platinum (cp) tail fails to sort correctly and corroborates the in situ findings in cp homozygous mutant mice. Correct sorting of tyrosinase-lysosome-associated membrane protein-1 chimeras is mediated by the interplay of a di-leucine signal and a tyrosine motif of the Y-X-X-O type.
authors.affiliation: Institute of Biochemistry, University of Lausanne, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Simmen
authors.forename: A
authors.initials: A
authors.lastname: Schmidt
authors.forename: W
authors.initials: W
authors.lastname: Hunziker
authors.forename: F
authors.initials: F
authors.lastname: Beermann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002460:Cell Line; D004285:Dogs; D004705:Endocytosis / Q000502:physiology; D005455:Fluorescent Antibody Technique; D007930:Leucine / Q000502:physiology*; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000378:metabolism*; D020460:Melanosomes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D014443:Tyrosine / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D014442:Monophenol Monooxygenase; D007930:Leucine