The 12 kD FK506 Binding Protein FKBP12 Is Released in the Male Reproductive Tract and Stimulates Sperm Motility

Table 1 [ ³ H] FK506 binding in the male reproductive tract and other selected tissues

The soluble fractions of male reproductive and other selected tissues (1–25 µg protein) were incubated with 250 pM [³H]FK506 in binding buffer (50 mM Trizma pH 7.4, 2 mg/ml BSA) for 60 min at room temperature. The reaction volume was layered over a 1.0-ml column of LH-20 Sephadex, the column was washed with 0.5 ml of buffer, and the eluates were collected and counted. Specific binding was determined by subtracting [³H]FK506 bound in the presence of up to 1 µM unlabeled FK506 from total [³H]FK506 bound. All binding experiments were done in duplicate and repeated three times.

ISSN: 1528-3658