cDNA cloning and baculovirus expression of the human liver endoplasmic reticulum P58: Characterization as a protein disulfide isomerase isoform, but not as a protease or a carnitine acyltransferase

Mohammed Bourdi, Damon Demady, Jackie L. Martin, Salma K. Jabbour, Brian M. Martin, John W. George, Lance R. Pohl

Research output: Contribution to journalArticlepeer-review

Abstract

The function of a 58-kDa liver microsomal protein (P58) is controversial. To help clarify the physiological function of this protein, particularly in humans, a full-length human liver cDNA clone was isolated, sequenced, and expressed in milligram quantities with the use of a baculovirus expression system. The deduced amino acid sequence of the mature protein contained two thioredoxin-like active site motifs (CGHC) and in its C-terminus a nuclear localization motif (KPKKKKK), and an ER-retention/retrieval motif (QEDL). The mature form of human P58 shared 95% amino acid sequence identity with the deduced amino acid sequences of a bovine liver cDNA, 93% with a murine B lymphocyte cDNA, and 91% with a rat basophilic leukemia cell cDNA. In contrast to reports on the activities of nonhuman forms of P58, the purified expressed human P58 showed no carnitine acyltransferase or protease activities. However, it did have protein disulfide isomerase activity, indicating that the physiological activity of human liver P58 may be attributed, at least in part, to this activity.

Original languageEnglish (US)
Pages (from-to)397-403
Number of pages7
JournalArchives of Biochemistry and Biophysics
Volume323
Issue number2
DOIs
StatePublished - Nov 10 1995

Keywords

  • Baculovirus expression system
  • Carnitine acyltransferase
  • Endoplasmic reticulum
  • Human liver
  • Protease
  • Protein disulfide isomerase isoform

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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