Molecular characterization of three rat liver serine-protease inhibitors affected by inflammation and hypophysectomy. Protein and mRNA analysis and cDNA cloning.
Rat hepatocytes have the potential to secrete three similar acidic glycoproteins, serine protease inhibitors 1, 2 and 3 (SPI-1, SPI-2, SPI-3), recognized by the same antibodies. They were synthesized as precursors of comparable sizes (45 kDa), which were post-translationally modified by N-glycosylation at three (SPI-3) or four (SPI-1 and SPI-2) sites. This appeared to account for the size difference of mature proteins. The mRNA sequences, derived from cDNA clones, displayed a high degree of similarity (70-90%), except the sequence of the antiprotease-reactive centers which were completely divergent. SPI-1 and SPI-2 mRNAs were of similar sizes (1.8 kb), and were smaller than that of SPI-3 (2.2 kb); the difference corresponded to a longer, 3'-end untranslated sequence. Production of SPI-1 and SPI-2, which was constitutive in the normal animal, could be abolished by hypophysectomy and was strongly decreased during acute inflammation. In contrast, production of SPI-3, which was barely detectable in normal rats, was transiently induced during inflammation.
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Laboratoire de Pharmacologie-Endocrinologie, Centre National de la Recherche Scientifique, Montpellier, France.
Rouayrenc
J F
JF
Le Cam
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Mariller
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Le Cam
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D000209:Acute-Phase Proteins / Q000235:genetics*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification*; D006023:Glycoproteins / Q000235:genetics* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007016:Hypophysectomy; D008099:Liver / Q000032:analysis*; D008297:Male; D008969:Molecular Sequence Data; D010316:Particle Size; D010902:Pituitary Gland / Q000502:physiology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000302:isolation & purification*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D015842:Serine Proteinase Inhibitors / Q000302:isolation & purification*
D000209:Acute-Phase Proteins; D000596:Amino Acids; D006023:Glycoproteins; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; D004247:DNA