title: Porcine dentin sialophosphoprotein: length polymorphisms, glycosylation, phosphorylation, and stability.
abstract: Dentin sialophosphoprotein (DSPP) is critical for proper mineralization of tooth dentin, and mutations in DSPP cause inherited dentin defects. Dentin phosphoprotein (DPP) is the C-terminal cleavage product of DSPP that binds collagen and induces intrafibrillar mineralization. We isolated DPP from individual pigs and determined that its N-terminal and C-terminal domains are glycosylated and that DPP averages 155 phosphates per molecule. Porcine DPP is unstable at low pH and high temperatures, and complexing with collagen improves its stability. Surprisingly, we observed DPP size variations on SDS-PAGE for DPP isolated from individual pigs. These variations are not caused by differences in proteolytic processing or degrees of phosphorylation or glycosylation, but rather to allelic variations in Dspp. Characterization of the DPP coding region identified 4 allelic variants. Among the 4 alleles, 27 sequence variations were identified, including 16 length polymorphisms ranging from 3 to 63 nucleotides. None of the length variations shifted the reading frame, and all localized to the highly redundant region of the DPP code. The 4 alleles encode DPP domains having 551, 575, 589, or 594 amino acids and completely explain the DPP size variations. DPP length variations are polymorphic and are not associated with dentin defects.
authors: Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48108, USA.
authors: Yasuo
authors: Y
authors: Yamakoshi
authors: Yuhe
authors: Y
authors: Lu
authors: Jan C-C
authors: JC
authors: Hu
authors: Jung-Wook
authors: JW
authors: Kim
authors: Takanori
authors: T
authors: Iwata
authors: Kazuyuki
authors: K
authors: Kobayashi
authors: Takatoshi
authors: T
authors: Nagano
authors: Fumiko
authors: F
authors: Yamakoshi
authors: Yuanyuan
authors: Y
authors: Hu
authors: Makoto
authors: M
authors: Fukae
authors: James P
authors: JP
authors: Simmer
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D003804:Dentin / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011110:Polymorphism, Genetic / Q000235:genetics*; D011489:Protein Denaturation; D011499:Protein Processing, Post-Translational; D016415:Sequence Alignment; D013552:Swine; D013696:Temperature
chemical_list: D016326:Extracellular Matrix Proteins