High impact information on PSP-I

• We report the crystal structures of porcine seminal plasma PSP-I/PSP-II, a heterodimer of two glycosylated spermadhesins, and bovine aSFP at 2.4 A and 1.9 A resolution respectively [1].
• The crystal structure of porcine seminal plasma spermadhesin PSP-I/PSP-II heterodimer has been determined in two crystal forms by multiple isomorphous replacement in an hexagonal crystal (space group P6(1)22) and molecular replacement in a trigonal crystal of space group P3(2)21 [2].
• Only the innermost N-acetylglucosamine of PSP-I is defined in the crystal structure [2].
• Thus, the modulation of the structural organization and heparin-binding ability of PSP-I by Zn2+ might be a physiological phenomenon in seminal plasma [3].
• Moreover, the viability, motility, and mitochondrial activity all decreased on incubation of spermatozoa with mixtures of PSP-I/PSP-II and heparin-binding spermadhesins as the concentration of the latter increased [4].

Biological context of PSP-I

• Nucleotide sequence analysis of the 706-bp PSP-I cDNA predicts a precursor protein of 133 amino acid residues, which includes a 21-residue signal peptide and a 112-residue secreted protein [5].
• Two full-length cDNAs encoding porcine seminal proteins, PSP-I and PSP-II, have been isolated from a porcine seminal vesicle cDNA library [5].
• Using biotinylated PSP-I, PSP binding sites were localized on approximately 3-5% of the lymphocyte population [6].
• Our results show that dimerization of spermadhesins PSP-I and PSP-II markedly affects their binding capabilities [7].
• The complete amino acid sequence of PSP-I has been determined by automated Edman degradation of peptides generated by proteolytic digestion and cyanogen bromide cleavage [8].

Anatomical context of PSP-I

• One component is identical with PSP-I, a major porcine seminal plasma protein whose function has not yet been identified, while the second protein is a glycosylated isoform of AQN-3 [9].
• In conclusion, the results confirm that exposure of fresh or frozen-thawed boar spermatozoa to a low dose of seminal PSP-I/PSP-II spermadhesin preserves sperm viability and motility in vitro [10].
• Does seminal plasma PSP-I/PSP-II spermadhesin modulate the ability of boar spermatozoa to penetrate homologous oocytes in vitro [10]?
• PSP-I showed additional signals in caput epididymis and rete testis [11].
• Macrophages and mast cells were isolated, cultured, and stimulated with purified PSP-I/PSP-II [12].

Associations of PSP-I with chemical compounds

• PSP-I and PSP-II are N-glycosylated at asparagine residues 50 and 98, respectively, and show site heterogeneity [2].
• The 2.4 A resolution crystal structure of boar seminal plasma PSP-I/PSP-II: a zona pellucida-binding glycoprotein heterodimer of the spermadhesin family built by a CUB domain architecture [2].
• Heterodimer formation with PSP-I abolishes both the heparin and the mannose-6-phosphate binding capabilities, suggesting that the corresponding sites may be located at the dimer interface [13].
• The protein or carbohydrate structures were not critical in the binding, since polyvinyl sulfate could effectively inhibit the binding of PSP-I to these proteins [14].
• Two major glycoproteins, designated PSP-I and PSP-II, were purified from porcine seminal plasma by ammonium sulfate fractionation, CM-cellulose chromatography, gel filtration on Sephadex G-75 (superfine), and reverse phase high performance liquid chromatography [8].

Physical interactions of PSP-I

• The complex of porcine seminal plasma heterodimers I and II (PSP-I/PSP-II), which are heterodimers of glycosylated spermadhesins, is the major component of porcine seminal fluid [12].
• PSP-I was found to bind a number of proteins including endo-beta-galactosidase digested ZP3, soybean trypsin inhibitor, IgA, IgG and alpha-casein, indicating that it may have multiple functions [14].

Other interactions of PSP-I

• Low concentration (0.15 mg per million of spermatozoa) of seminal plasma-derived PSP-I/PSP-II spermadhesin heterodimer is able to preserve the viability of highly extended boar spermatozoa [10].
• In the present study, we have investigated the involvement of macrophages and mast cells in the neutrophil chemotactic activity of PSP-I/PSP-II and the underlying mechanism [12].

Analytical, diagnostic and therapeutic context of PSP-I

• When cryopreserved spermatozoa were tested, however, on IVM oocytes, already a 30-minute preincubation exposure to PSP-I/PSP-II showed a significant blocking effect on penetration rate (from 90% to 32%, P < .05) and on mean sperm numbers per oocyte (2.9 to 1.6, P < .05) [10].
• Molecular cloning and sequence analysis of two porcine seminal proteins, PSP-I and PSP-II: new members of the spermadhesin family [5].
• Crystallization and preliminary X-ray diffraction analysis of boar seminal plasma spermadhesin PSP-I/PSP-II, a heterodimer of two CUB domains [15].
• The finding that PSP-I/PSP-II contributes to maintaining sperm with high viability, motility, and mitochondrial activity for at least 5 h at physiological temperature points to its potential use as an additive for sperm preservation, specifically of highly diluted, flow-sorted spermatozoa for sex preselection [4].
• In this study, we have investigated the possible biological functions of PSP-I using a solid-phase protein binding assay and its site of synthesis using both Western blot and immunocytochemical analyses [14].

References