May 10, 1996

Isolation and characterization of a folate receptor-directed metalloprotease from human placenta

The Journal of Biological Chemistry
X Y YangA C Antony

Abstract

Glycosyl-phosphatidylinositol-anchored hydrophobic placental folate receptors (PFRs), which have an important functional role in maternal-to-fetal transplacental folate transport, can be converted to soluble hydrophilic forms by a placental metalloprotease. Using a Triton X-114 temperature-induced phase separation assay to monitor enzyme-mediated conversion of radiolabeled hydrophobic PFR into hydrophilic PFR, a metalloenzyme was isolated to apparent homogeneity from Triton X-114-solubilized human placenta using concanavalin A-Sepharose and reverse-phase high performance liquid chromatography (HPLC) as major purification steps. The purified hydrophobic enzyme eluted as a single protein peak on reverse-phase HPLC and SDS-polyacrylamide gel electrophoresis revealed a single 63,000 M(r) species, which was reduced to 58,000 M(r) following deglycosylation, findings comparable with amino acid analysis (M(r) approximately 59,000). The metalloenzyme was activated by Mg2+, Zn2+, Mn2+, and Ca2+, optimally at physiologic pH; it also exhibited EDTA-sensitive endoproteolytic cleavage of [3H]leucine-labeled full-length nascent PFR polypeptide generated in vitro in the absence of microsomes. Rabbit polyclonal anti-metalloprotease antiserum sp...Continue Reading

Mentioned in this Paper

Cations, Divalent
Placenta Specimen
Placenta Disorders
Hormone Receptors, Cell Surface
Microsomes
SDS-PAGE
Immune Sera
Placenta
Cytokinesis of the Fertilized Ovum
Cross Reactions

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