| Autor: |
Sprecher, Cindy A., Morgenstern, Kurt A., Mathewes, Shannon, Dahlen, Jeffrey R., Schrader, Sara K., Foster, Donald C., Kisiel, Walter |
| Zdroj: |
Journal of Biological Chemistry; December 1995, Vol. 270 Issue: 50 p29854-29861, 8p |
| Abstrakt: |
A human placental λgt11 cDNA library was screened for sequences encoding proteins related to human proteinase inhibitor 6 (PI6), and two plaques were identified that displayed weak hybridization at high stringency. Isolation and characterization of the DNA inserts revealed two novel sequences encoding proteins composed of 376 and 374 amino acids with predicted molecular masses of ~42 kDa. The novel proteins displayed all of the structural features unique to the ovalbumin family of intracellular serpins including the apparent absence of a cleavable N-terminal signal sequence. The degree of amino acid sequence identity between the novel serpins and PI6 (63-68%) significantly exceeds that of any other combination of known intracellular serpins. The two novel serpins encoded by the two novel cDNA sequences have been designated as proteinase inhibitor 8 (PI8) and proteinase inhibitor 9 (PI9). The putative reactive center P1-P1′ residues for PI8 and PI9 were identified as Arg339-Cys340and Glu340-Cys341, respectively. PI9 appears to be unique in that it is the first human serpin identified with an acidic residue in the reactive center P1position. In addition, the reactive center loop of PI9 exhibits 54% identity with residues found in the reactive center loop of the cowpox virus CrmA serpin. Two PI8 transcripts of 1.4 kilobases (kb) and 3.8 kb were detected by Northern analysis in equal and greatest abundance in liver and lung, while the 1.4-kb mRNA was in excess over the 3.8-kb mRNA in skeletal muscle and heart. Two PI9 transcripts of 3.4 and 4.4 kb were detected in equal and greatest abundance in lung and placenta and were weakly detected in all other tissues. |
| Databáze: |
Supplemental Index |
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