Binder of sperm protein homolog 1 is a protein that in humans is encoded by the BSPH1 gene. It contains two fibronectin type II domains (Fn2 domains) linked in tandem by disulfide bonds.[5][6] BSPH1 is a member of the BSP protein superfamily along with bovine PDC-109.[7]
Function
The BSPH1 protein performs various roles in sperm function, primarily through binding of the sperm membrane. This is done through its Fn2 domains, which bind choline phospholipids on the membranes' surfaces.[8] Binding occurs in the epididymis prior to ejaculation, and acts to stabilize the sperm.
After ejaculation and entry of sperm into the oviduct, the protein facilitates capacitation, a key step in egg fertilization.[5] Here, it acts in conjunction with oviductal cholesterol acceptors, such as albumin and HDL, to remove cholesterol from the sperm membrane in a cholesterol efflux. With the loss of cholesterol, glycosylphosphatidylinositol-anchor proteins (GPI-APs) become destabilized, increasing membrane fluidity, resulting in the release of BSPH1.[9][10]
References
- ^ a b c GRCh38: Ensembl release 89: ENSG00000188334 – Ensembl, May 2017
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000074378 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ a b "Entrez Gene: BSPH1 binder of sperm protein homolog 1".
- ^ Lefebvre J, Boileau G, Manjunath P (February 2009). "Recombinant expression and affinity purification of a novel epididymal human sperm-binding protein, BSPH1". Molecular Human Reproduction. 15 (2): 105–114. doi:10.1093/molehr/gan077. PMID 19091820.
- ^ Manjunath P, Lefebvre J, Jois PS, Fan J, Wright MW (March 2009). "New nomenclature for mammalian BSP genes". Biology of Reproduction. 80 (3): 394–397. doi:10.1095/biolreprod.108.074088. PMC 2844493. PMID 18923155.
- ^ Manjunath P, Thérien I (January 2002). "Role of seminal plasma phospholipid-binding proteins in sperm membrane lipid modification that occurs during capacitation". Journal of Reproductive Immunology. 53 (1–2): 109–119. doi:10.1016/S0165-0378(01)00098-5. PMID 11730909.
- ^ Plante G, Thérien I, Lachance C, Leclerc P, Fan J, Manjunath P (May 2014). "Implication of the human Binder of SPerm Homolog 1 (BSPH1) protein in capacitation". Molecular Human Reproduction. 20 (5): 409–421. doi:10.1093/molehr/gau006. PMID 24435510.
- ^ Puga Molina LC, Luque GM, Balestrini PA, Marín-Briggiler CI, Romarowski A, Buffone MG (2018-07-27). "Molecular Basis of Human Sperm Capacitation". Frontiers in Cell and Developmental Biology. 6 72. doi:10.3389/fcell.2018.00072. PMC 6078053. PMID 30105226.