title: A novel rat dentin mRNA coding only for dentin sialoprotein.
abstract: Dentin sialoprotein (DSP) is a major glycoprotein present in the mineralized dentin matrix that is expressed mainly by young and mature odontoblasts. Mutations in the DSP coding regions are linked to Dentinogenesis imperfecta I and II. indicating the importance of DSP in tooth formation. Previous studies have identified multiple mRNA transcripts in dentin that code for both DSP and phosphophoryns (PPs). Using reverse transcriptase-polymerase chain reaction (RT-PCR) to characterize these mRNA transcripts, we have identified a cDNA that codes for DSP, but not PP. This cDNA codes for a protein with 324 amino acids, 303 amino acids being identical to the published rat DSP sequence. However, the subsequent 21 amino acids are unique to this cDNA. Based on the coding sequence, the core protein is predicted to have a pI=4.24, a net charge of -34, and to contain four potential N-glycosylation sites and six potential sites for phosphorylation by casein kinase. That the corresponding mRNA was present in day 5 molar tooth germs was confirmed using RNA protection assays. These data, therefore, identify a novel transcript in rat tooth germs that codes only for DSP (designated as DSPII).
authors.affiliation: Department of Cariology, Restorative Sciences and Endodontics, University of Michigan School of Dentistry, Ann Arbor 48109, USA. helenar@umich.edu
authors.forename: H H
authors.initials: HH
authors.lastname: Ritchie
authors.forename: X
authors.initials: X
authors.lastname: Li
mesh_terms: D000367:Age Factors; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D015139:Blotting, Southern; D047388:Casein Kinases; D018076:DNA, Complementary / Q000235:genetics; D003804:Dentin / Q000378:metabolism*; D003810:Dentinogenesis / Q000235:genetics; D016326:Extracellular Matrix Proteins; D007527:Isoenzymes / Q000378:metabolism; D008963:Molar; D009693:Nucleic Acid Hybridization; D009804:Odontoblasts / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011498:Protein Precursors; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D012795:Sialoglycoproteins / Q000145:classification / Q000235:genetics*; D014083:Tooth Germ / Q000378:metabolism; D014158:Transcription, Genetic; D000099311:Dentin Sialophosphoprotein
chemical_list: D000596:Amino Acids; D047388:Casein Kinases; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D007527:Isoenzymes; D010750:Phosphoproteins; D011494:Protein Kinases; D011498:Protein Precursors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein; C017630:phosphophoryn