Immuno precipitation of biotinylated human sperm proteins with rabbit antiserum against the HSP70-like membrane protein of Chlamydia trachomatis (ctHSP70).
Biotin-labelled sperm proteins precipitated with preimmune rabbit serum (left) and antiserum (right) against a putative peptide interaction domain of sea urchin sperm receptor (represented by aa 351–368 of ctHSP70). Immuno precipitated surface biotinylated proteins were detected by affinity staining with HRP-avidin. While abundant ~60 kDa and ~80–90 kDa sperm surface antigens were specifically purified with the anti-ctHSP70 antiserum, a common 65 kDa surface antigen was immune-precipitated with both the preimmune serum and the antiserum. However, computer densitometry analysis revealed that approximately four times more biotin labelled 65 kDa protein was isolated with the anti-ctHSP70 antiserum, compared to that precipitated with similar amounts of preimmune serum.