Constitutive biosynthesis of bone Gla protein in a human osteosarcoma cell line.
A human osteosarcoma cell line derived from cells obtained from a patient with Paget's disease is shown to synthesize and secrete bone Gla protein (BGP); (osteocalcin), a noncollagenous bone matrix protein. Using a human BGP-specific RIA, we show that the human osteosarcoma cells synthesize significant amounts of BGP without any prior induction of BGP synthesis by 1,25-dihydroxyvitamin D. After specific immunoprecipitation of poly-A+ RNA in vitro translation products with antibodies to BGP, we found that BGP is synthesized as a precursor with an apparent mol wt of 13.5K, as demonstrated on 15% sodium dodecyl sulfate-polyacrylamide gels. Finally, pulse labeling of the osteosarcoma cells with [3H]proline reveals that the cells synthesize mature BGP of 12,000 mol wt as well as a higher mol wt precursor (13,500) of the protein.
G C
GC
Kaplan
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G
Eilon
J W
JW
Poser
J W
JW
Jacobs
D001345:Autoradiography; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008832:Microchemistry / Q000379:methods; D008970:Molecular Weight; D015675:Osteocalcin; D012516:Osteosarcoma / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger; D011863:Radioimmunoassay
D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; D015675:Osteocalcin; D011061:Poly A; D012313:RNA; D011392:Proline