Figure 3From: Identification of calcium-binding proteins associated with the human sperm plasma membraneSAP is a 45 Ca-binding protein exposed on the surface of human sperm. Immuno-staining of PVDF membranes used to detect radioiodinated surface proteins (A) and 45Ca-binding proteins (C) by autoradiography confirmed that the 26.5 kDa calcium binding surface protein with a pI of 5.2 (oblique downward arrows) is SAP (B & D).Back to article page