High impact information on AWN

• Binding of ejaculated sperm to oviductal epithelium was inhibited by addition of AQN1 but not by AWN [1].
• AQN1 showed a broad carbohydrate-binding pattern as it recognizes both alpha- and beta-linked galactose as well as Manalpha1-3(Manalpha1-6)Man structures, whereas AWN bound only the galactose species [1].
• Clusters of AWN epitopes were occasionally found attached to the epithelium of the uterotubal junction and the adjacent lower isthmus [2].
• In addition, the complete amino acid sequence of spermadhesin AWN was synthesized as overlapping peptides, and their ability to bind to a heparin-Sepharose column and to inhibit the interaction of soluble heparin with purified ELISA plate-coated AWN was tested [3].
• Both approaches gave similar results and as a whole showed that different regions of AWN may converge in its tertiary structure to form a composite heparin-binding site [3].

Biological context of AWN

• These results suggest that under physiological conditions, the aggregates of seminal plasma proteins (DQH, AQN, AWN, PSP II) rather than the individual proteins might take part in coating the sperm surface, in sperm capacitation, and in primary binding of spermatozoa to zona pellucida of the ovum [4].

Anatomical context of AWN

• Remarkably, AWN is the only spermadhesin that is also expressed in the uterus, the uterotubal junction, and the oviduct of the female genital tract as shown by RT-PCR, cDNA-sequencing, and immunological analysis [5].
• Boar spermadhesins AQN-1, AQN-3 and AWN form a recently described protein family, synthesized by the sexual accessory glands, and become associated with the sperm head upon ejaculation [6].
• The complete primary structure of the spermadhesin AWN, a zona pellucida-binding protein isolated from boar spermatozoa [7].
• The strongest interaction was observed between biotinylated glycoproteins of porcine zona pellucida and AWN 1-containing aggregates and separated proteins [4].
• Spermadhesins of the AQN and AWN families, DQH sperm surface protein and HNK protein in the heparin-binding fraction of boar seminal plasma [8].

Associations of AWN with chemical compounds

• The amino acid sequence of AWN contains 133 amino acid residues and two disulphide bridges between nearest-neighbour cysteine residues [7].
• Aggregates containing AWN, AQN, DQH, PSP II proteins, and their separated monomeric forms (fractions I-III) interacted with phosphorylcholine [4].
• Affinity chromatography experiments showed that the DQH protein bound to gelatin-agarose together with the AWN proteins and that the DQH protein and AQN-1 spermadhesin belong to the phosphoryl choline binding proteins [8].
• Using a synthetic peptide approach we show that the regions of spermadhesin AWN comprising residues 6-12 and 104-108 possess affinity for phosphorylethanolamine [9].

Other interactions of AWN

• During sperm passage through the epididymis AQN-3 and AWN have been shown to bind tightly to the sperm surface by interaction with the phospholipids of the membrane bilayer [10].
• HPLC analysis and N-terminal sequencing used to characterize the composition of the protein fractions obtained by gel chromatography revealed that all consisted of low (12-16 kDa) molecular weight components: the H+ fraction consisted of DQH sperm protein, AQN and AWN spermadhesins whereas the H- fraction consisted of PSPI and PSPII spermadhesins [11].
• Boar spermadhesins AQN-1 and AWN are sperm-associated acrosin inhibitor acceptor proteins [12].
• Biotinylated aggregates containing AWN, AQN, DQH, and PSP proteins (fractions I-IV) bound stronger to boar epididymal spermatozoa than to ejaculated spermatozoa [4].
• Therefore, basic protein BHB-2 belongs to a new family of DQH sperm surface proteins that are homologous to the acidic proteins from bull and stallion seminal plasma, to the collagen binding domain II in fibronectin and to the leucocyte cell-cell adhesion regulator, but are not homologous to AQN or AWN spermadhesins [8].

Analytical, diagnostic and therapeutic context of AWN

• Translation can be detected only for AWN in tissue extracts by SDS-PAGE and Western blotting [5].
• In addition, the amount of spermadhesins AQN-1, AQN-2, and AQN-3 relative to that of AWN was determined by amino acid analysis after reverse-phase HPLC isolation [13].
• In addition, immunoblotting analysis has shown that AWN is present on epididymal spermatozoa [14].
• Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover the entire acrosomal cap membrane [15].
• In the present study, spermadhesin AWN in unfixed living suspensions of boar spermatozoa was assessed by means of flow cytometry and immunocytochemistry, using a polyclonal antibody raised in chicken [16].

References