title: Evolutionary well-conserved region in the signal peptide of parathyroid hormone-related protein is critical for its dual localization through the regulation of ER translocation.
abstract: Parathyroid hormone-related protein (PTHrP) has two different targeting signals: an N-terminal signal peptide for the endoplasmic reticulum (ER) targeting and an internal nuclear localization signal. The protein not only functions as a secretory protein, but is also found in the nucleus and/or nucleolus under certain conditions. PTHrP signal peptide is less hydrophobic than most signal peptides mainly due to its evolutionarily well-conserved region (QQWS). The substitution of four tandem leucine residues for this conserved region resulted in a significant inhibition of the signal peptide cleavage. At the same time, proportion of nuclear and/or nucleolar localization decreased, probably due to tethering of the protein to the ER membrane by the uncleaved mutant signal peptide. Almost complete cleavage of the signal peptide accompanied by a lack of nuclear/nucleolar localization was achieved by combining the hydrophobic h-region and an optimized sequence of the cleavage site. In addition, mutational modifications of the distribution of charged residues in and around the signal peptide affect its cleavage and/or nuclear/nucleolar localization of the protein. These results indicate that the well-conserved region in the signal peptide plays an essential role in the dual localization of PTHrP through ER targeting and/or the membrane translocation.
authors.affiliation: Division of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan and amaya@dent.niigata-u.ac.jp.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Amaya
authors.affiliation: Radioisotope Research Center, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Nakai
authors.affiliation: Radioisotope Research Center, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Miura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002466:Cell Nucleolus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D015398:Signal Transduction; D013329:Structure-Activity Relationship
chemical_list: D019913:Nuclear Localization Signals; D044162:Parathyroid Hormone-Related Protein
keywords: endoplasmic reticulum; nuclear localization signal; parathyroid hormone-related protein; protein conducting channel; signal peptide