Identification of a high-affinity binder for estradiol and a low-affinity binder for testosterone in Coccidioides immitis

Abstract

Coccidioides immitis cytosol contains a specific estrogen binder with kinetic characteristics (Kd = 2.1 X 10(-8) to 3.7 X 10(-8) M; n = 0.5 to 1.56 pmol/mg of protein) appropriate for interaction with levels of estrogen encountered during pregnancy. The Kd of a separate androgen binder (ca. 10(-7) M) is probably too low to allow interaction with physiological levels of testosterone.