A comparative study of sialic acid-rich proteins in rat bone and dentin.
Four sialic acid-rich (SA-rich) proteins found in bone and dentin, osteopontin (OPN), bone sialoprotein (BSP), bone acidic glycoprotein-75 (BAG-75), and dentin matrix protein 1 (DMP1), share some common features. We used SDS-PAGE and Western immunoblots to analyze and compare SA-rich proteins in bone and dentin extracts from rats with a single chromatographic procedure. OPN was detected in dentin extracts, with a relative level less than one-seventieth of that in bone. Both bone and dentin BSP demonstrated an extremely broad distribution pattern, probably due to a high degree of heterogeneity in post-translational modifications. BAG-75 in both bone and dentin was detected as an 83 kDa band, dramatically distinct from that of DMPI. Using a polyclonal antibody raised against a purified bone 57 kDa protein (a portion of DMPI), we detected 150 kDa protein bands in bone fraction; the same bands were recognized by antirecombinant rat DMPI antibody. Bands from dentin migrating at about 150 kDa in earlier fractions and progressing to 200 kDa in later fractions showed a clear immunoreactivity to the anti-57 kDa antibody. We conclude that the majority of DMPI in rat bone is processed into fragments, whereas that in dentin remains intact.
Qin
C
C
Department of Basic Sciences, The University of Texas-Houston Health Science Center, Dental Branch, 77030, USA. cqin@mail.db.uth.tmc.edu
Brunn
J C
JC
Jones
J
J
George
A
A
Ramachandran
A
A
Gorski
J P
JP
Butler
W T
WT
D000818:Animals; D015153:Blotting, Western; D001842:Bone and Bones / Q000737:chemistry*; D002848:Chromatography, DEAE-Cellulose; D003804:Dentin / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000302:isolation & purification; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification; D058574:Integrin-Binding Sialoprotein; D008970:Molecular Weight; D053495:Osteopontin; D010750:Phosphoproteins / Q000737:chemistry / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D051381:Rats; D020539:Sequence Analysis, Protein; D012795:Sialoglycoproteins / Q000737:chemistry* / Q000302:isolation & purification
C513309:DMP1 protein, human; C081635:Dmp1 protein, rat; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C546871:IBSP protein, human; C546873:Ibsp protein, rat; D058574:Integrin-Binding Sialoprotein; D010750:Phosphoproteins; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; C512787:bone acidic glycoprotein-75, rat; D053495:Osteopontin