Human sperm CRISP2 is released from the acrosome during the acrosome reaction and re-associates at the equatorial segment.

Sperm CRISP2 has been proposed to be involved in sperm-egg fusion. After the acrosome reaction, it appears at the equatorial segment (EqS) of human sperm; the mechanism underlying the appearance of CRISP2 at the EqS remains unknown, though. Here, we provide evidence showing the re-association of sperm acrosomal CRISP2 at the EqS during the acrosome reaction.

Roles of mouse sperm-associated alpha-L-fucosidases in fertilization.

Sperm-associated α-L-fucosidases have been implicated in fertilization in many species. Previously, we documented the existence of α-L-fucosidase in mouse cauda epididymal contents, and showed that sperm-associated α-L-fucosidase is cryptically stored within the acrosome and reappears within the sperm equatorial segment after the acrosome reaction. The enrichment of sperm membrane-associated α-L-fucosidase within the equatorial segment of acrosome-reacted cells implicates its roles during fertilization.

Distribution, crypticity, stability, and localization of α-L-fucosidase of mouse cauda epididymal sperm.

Sperm-associated and semen-specific isoforms of α-L-fucosidase are thought to function in fertilization in numerous organisms. Here, we report the localization, distribution, crypticity, and stability of this enzyme in mouse cauda epididymal sperm and cauda fluid. Western analysis revealed that the sperm-associated α-L-fucosidase is present as two isoforms (Mr ∼49 and 56 kDa), whereas the cauda fluid α-L-fucosidase shows a single band at 50 kDa.

Hamster sperm-associated alpha-L-fucosidase functions during fertilization.

Sperm-associated alpha-L-fucosidases have been identified in diverse organisms. Their wide phylogenetic distribution and known properties support the likelihood that L-fucose and alpha-L-fucosidase have fundamental function(s) during gamete interaction. This is consistent with the substantial evidence in the literature documenting the importance of carbohydrate moieties during fertilization.

Stabilization of membrane-associated alpha-L-fucosidase by the human sperm equatorial segment.

Previous reports from this laboratory documented the existence of two novel isoforms of alpha-L-fucosidase in human semen and showed that membrane-associated alpha-L-fucosidase is cryptically held within the acrosomal compartment and enriched within the sperm equatorial segment. The occurrence of these novel isoforms is provocative. Sperm proteins potentially involved in sperm-egg interactions must maintain their functional integrity as they travel through the female reproductive tract.

Crypticity and functional distribution of the membrane associated alpha-L-fucosidase of human sperm.

Two distinctive isoforms of the enzyme alpha-L-fucosidase are found within human semen in substantial amounts, suggesting specialized functions during reproduction. The membrane-associated isozyme of human sperm cells was previously characterized biochemically, and here we report on its subcellular localization. Intact, detergent permeabilized, capacitated, and acrosome-reacted sperm were investigated using antifucosidase immunofluorescence, binding of the fluorescent fucosylated glycoconjugate RITC-BSA-fucose (RBF), and enzyme activity in the presence and absence of selected inhibitors.

Purification and characterization of plasma membrane-associated human sperm alpha-L-fucosidase.

Detergent and salt extraction studies, as well as cytochemical localization with fluorescein isothiocyanate-bovine serum albumin-L-fucose, have provided further evidence for the plasma membrane association of a novel human sperm, alpha-L-fucosidase. This alpha-L-fucosidase has been solubilized and purified 8600-fold to high specific activity (35 000 U/mg protein) by affinity chromatography on agarose-C(24)-fucosylamine. To our knowledge, this is the first report concerning the purification and characterization of a mammalian plasma membrane-associated alpha-L-fucosidase.

Purification and characterization of human seminal plasma alpha-L-fucosidase.

Human seminal plasma alpha-L-fucosidase (EC 3.2.1.