Figure 6. Ligand blot analysis of a whole-mouse sperm lysate for progesterone (P4)-binding/receptor proteins. Proteins were obtained from cauda sperm and were either incubated under capacitating conditions (C) or not under capacitating conditions (non-C), and caput sperm, either incubated (I) or nonincubated (non-I), were analyzed by 7%–10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) (right panel), blotted, and visualized using P4-peroxidase conjugate (left panel). Medium standard molecular-weight markers were run in parallel.