title: The presence of multiple rat DSP-PP transcripts.
abstract: Phosphoproteins or phosphophoryns (PPs) are the most abundant (>50%) non-collagenous proteins (NCPs) in dentin. PPs bind to calcium and hydroxyapatite and are believed to play a crucial role in dentin mineralization. Dentin sialoprotein (DSP), a highly glycosylated protein, comprised 5-8% of NCPs in dentin. The coding sequences for these two major NCPs are known to be contiguously located (i.e. DSP-PP) at the cDNA and genomic DNA levels in both rat and mouse. Previous studies have demonstrated the presence of multiple DSP-PP transcripts in the total RNA of adult rat incisors. To further understand the nature of these multiple transcripts, we performed reverse transcription-PCR and obtained a PP cDNA variant which encoded a 171 amino acid peptide (PP(171)) that shares many of the same characteristics as that of the published rat PP(240) sequence [Ritchie, H.H. and Wang, L.-H., J. Biol. Chem. 271 (1996) 21695-21698]. Due to its reduced size, as compared to PP(240), this cDNA encodes a phosphorylated protein with a reduced negative charge that may differentially affect mineralization processes. We provide evidence that there are multiple DSP-PP transcripts with various sizes of PP sequences in rat.
authors.affiliation: Department of Cardiology, Restorative Sciences and Endodontics, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48109-1078, USA. helenar@umich.edu
authors.forename: H H
authors.initials: HH
authors.lastname: Ritchie
authors.forename: L
authors.initials: L
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D047388:Casein Kinases; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D003804:Dentin / Q000737:chemistry*; D016326:Extracellular Matrix Proteins; D007180:Incisor / Q000737:chemistry*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000737:chemistry; D011494:Protein Kinases / Q000737:chemistry; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000235:genetics; D000099311:Dentin Sialophosphoprotein
chemical_list: D000596:Amino Acids; D047388:Casein Kinases; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D011494:Protein Kinases; D011498:Protein Precursors; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein; C017630:phosphophoryn