Molecular identification of adrenal inner zone antigen as a heme-binding protein

Li Min, Natallia V. Strushkevich, Ivan N. Harnastai, Hiroko Iwamoto, Andrei A. Gilep, Hiroshi Takemori, Sergey A. Usanov, Yasuki Nonaka, Hiroshi Hori, Gavin P. Vinson, Mitsuhiro Okamoto

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)

Abstract

The adrenal inner zone antigen (IZA), which reacts specifically with a monoclonal antibody raised against the fasciculata and reticularis zones of the rat adrenal, was previously found to be identical with a protein variously named 25-Dx and membrane-associated progesterone receptor. IZA was purified as a glutathione 5-transferase-fused or His6-fused protein, and its molecular properties were studied. The UV-visible absorption and EPR spectra of the purified protein showed that IZA bound a heme chromophore in high-spin type. Analysis of the heme indicated that it is of the b type. Site-directed mutagenesis studies were performed to identify the amino-acid residues that bind the heme to the protein. The results suggest that two Tyr residues, Tyr107 and Tyr113, and a peptide stretch, D99-K102, were important for anchoring the heme into a hydrophobic pocket. The effect of IZA on the steroid 21-hydroxylation reaction was investigated in COS-7 cell expression systems. The results suggest that the coexistence of IZA with CYP21 enhances 21-hydroxylase activity.

Original languageEnglish
Pages (from-to)5832-5843
Number of pages12
JournalFEBS Journal
Volume272
Issue number22
DOIs
Publication statusPublished - Nov 2005
Externally publishedYes

Keywords

  • Adrenal inner zone antigen
  • Heme-binding protein
  • Membrane-associated progesterone receptor
  • Steroidogenesis
  • Zonae fasciculata and reticularis

Fingerprint

Dive into the research topics of 'Molecular identification of adrenal inner zone antigen as a heme-binding protein'. Together they form a unique fingerprint.

Cite this