Binder of sperm protein homolog 1 (BSPH1)

Binder of sperm protein homolog 1 (BSPH1) is a secreted protein primarily expressed in the epididymal tissues of mammals, including humans and mice, where it is involved in the maturation and functional development (capacitation) of sperm[1][3][5]. This protein is part of the larger binder of sperm (BSP) protein family, whose members are known to bind choline phospholipids on sperm membranes and promote sperm’s ability to fertilize an oocyte[1][3]. In experimental models, BSPH1 binds to components like gelatin, heparin, and phosphatidylcholine, suggesting it facilitates interactions critical for sperm function[3][5]. Despite its biochemical role in sperm capacitation, studies in knockout mice lacking both Bsph1 and its related paralog Bsph2 showed no impact on male fertility or sperm motility, though subtle effects on offspring phenotype (such as pup weight) were detected[3]. BSPH1 does not appear to function as a classical receptor, enzyme, or transporter, and there are no therapeutics or biomarker roles associated with it in current literature[5]. It is not considered a therapeutic target.

Other names

BSPH1Binder of sperm protein family member 1Epididymal secretory protein E1 (in older literature)

Not applicable (No known drugs target BSPH1 directly)