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Detection of a heat‐ and acid‐stable ‘progesterone’‐binding protein in the rat lung
Author(s) -
Moser Ewald H.,
Daxenbichler Günter
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)80766-7
Subject(s) - cytosol , chemistry , steroid , biochemistry , enzyme , binding site , cleavage (geology) , receptor , binding protein , progesterone receptor , plasma protein binding , biology , hormone , gene , genetics , cancer , estrogen receptor , breast cancer , paleontology , fracture (geology)
Using a modified charcoal method, we could detect a steroid‐binding component in rat lung cytosol which specifically binds R5020, progesterone, and some of its natural derivatives. The concentration of binding sites is high (30–40 pmol/mg protein), the affinity is moderate, the K d of the R5020 complex being ∼10 −7 M. Proteolytic enzymes and sulfhydryl reagents destroyed the binding sites indicating the protein nature and the requirement for disulfide bonds. The protein sedimented in the 2 S range thus had an M r of 10 000–15 000. Further characteristics are the extreme heat (30 min at 100°C) and acid (pH 1) stability. These properties and the fact that it was not detected in serum, distinguish this binding protein from receptors and specific serum steroid binders.