Are there two forms of β2-N-acetylglucosaminyltransferase I in rat testicular and epididymal fluids?

Nozaki, Hirofumi; Matsuzawa, Takeo; Nakamura, Tadashi; Arai, Ikichi; Urashima, Tadasu

doi:10.1016/s1570-9639(03)00165-1

Cited by 4 publications

(5 citation statements)

References 26 publications

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“…The properties of this enzyme activity, such as optimum pH and requirement for bivalent cations, were similar to those for the GnT I activities of rat liver, 27) rabbit liver 28) as well as rat testicular fluid 16) showing that this enzyme is GnT I, but were different from those for rat epididymal fluid 16) as shown in Table 1. The enzyme has the substrate specificities for 1 3 1 6 mannopentaose, 1 3 1 6 mannotriose, and 1 3 mannobiose, but not for 1 6 mannobiose; this is typical substrate specificity for GnT I.…”

Section: Discussionsupporting

confidence: 51%

“…GnT I activity was assayed by measuring the incorporation of [ 3 H] GlcNAc into the substrate mannopentaose, as described previously for GnT I in rat testicular and epididymal fluid. 16) The incubation mixture (100 L) consisted of 50 mM sodium cacodylate buffer (pH 5. The concentration of protein in bFF was determined by the Lowry method 26) using bovine serum albumin as the standard.…”

Section: Methodsmentioning

confidence: 99%

“…Those which are type II membrane proteins are generally localized in the Golgi apparatus 14) and it has been reported that some of these enzymes are released through cleavage by an endogenous protease or proteases, and are then secreted from the cell. 15) Indeed, many glycosyltransferases have been detected as soluble forms in extracellular fluids such as testicular and epididymal fluids, 16) uterine and oviductal fluids 17) as well as in serum, 18,19) colostrum, 20) amniotic fluid and milk. 21) It has been documented, in addition, that proteolytic cleavage and secretion of glycosyltransferases into extracellular fluids are affected in various pathological conditions such as malignancy and inflammation 15,17,18) as well as the progress of the estrous cycle.…”

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confidence: 99%

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N-Acetylglucosaminyltransferase I Activity in Bovine Ovarian Follicular Fluids from Dominant and Atretic Follicles

浩文¹,

明夫²,

憲悟³

et al. 2004

J. Appl. Glycosci.

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The activity of α3 D mannoside 1,2 N acetylglucosaminyltransferase I (GnT I; EC 2.4.1.101), which catalyzes the first step in the conversion of oligomannose to complex or hybrid N glycans of glycoproteins, was detected in bovine follicular fluid (bFF). The GnT I activity in bFF had a pH optimum of 5.8 and an absolute requirement for either Co 2 , Mn 2 , or Mg 2 , the activity being stimulated by these cations in the above order. The apparent Km value for α1 3α1 6 mannopentaose of GnT I in bFF was 2.17 mM. The substrate specificity for the GnT I activity decreased in the following order: α1 3α1 6 mannopentaose α1 3α1 6 mannotriose α1 3 mannobiose. The GnT I activity in bFF from large atretic follicles was significantly higher than in that from large dominant follicles. Moreover there was no significant difference between the GnT I activities in bFF from dominant follicles collected before and after surge of luteinizing hormone (LH surge). These data suggest that the GnT I activity in bFF may reflect functional changes in the microenvironment which lead to follicular atresia.

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Section: Discussionsupporting

confidence: 51%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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N-Acetylglucosaminyltransferase I Activity in Bovine Ovarian Follicular Fluids from Dominant and Atretic Follicles

浩文¹,

明夫²,

憲悟³

et al. 2004

J. Appl. Glycosci.

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“…The apparent Km value for 41-3 a 1-6mannopentose ofGnT I in the testicular and epididymal fluids was 0.57 and 0.38 rnM, respectively. This suggestedthat two forms of GnT I exist in the testicular and epididymal fluids (Nozaki et al, 2003).…”

Section: Other Glycosyl Transferases DL 2-n-acetyl Glucosaminyl Tranmentioning

confidence: 99%

Acrosomal Enzymes

Gupta

2005

Proteomics of Spermatogenesis

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Sperm-egg interaction is a species-specific event, which is initiated by the recognition and binding of complementary molecule(s) present on sperm surface (receptor) and the surface of the zona-pellucida (ZP ligand). This is a carbohydrate-mediated signal transduction event, which is believed to be a pre-requisite that enables the acrosome reacted spermatozoa to penetrate the ZP before the egg is fertilized. The hydrolytic enzymes released at the site of sperm-egg binding, alongwith the enhanced thrust generated by the hyperactivation of the bound spermatozoa are important factors that regulate the penetration of wna pellucida and fusion of the gametes. Evidences strongly suggest that sperm-egg binding leading to the acrosomal exocytosis is a complex event that likely reflects interaction between multiple sperm surface receptors and multivalent ZP. The ZP in a species is composed of three glycoproteins namely, ZP1, ZP2, and ZP3. These glycoproteins at least in the mouse are synthesized and secreted during oogenesis. It is generally accepted that hydrolytic enzymes, such as arylsulfatase, &glucuronidase, N-acetylglucosaminidase and hyaluronidase, and perhaps proteases aid in the process of dispersion of the cumulus mass by hydrolyzing hyaluronic acid andlor polypeptide substrates. The protease group of enzymes includes serine proteases, proacrosin, acrosin, metalloproteases, ADAM proteins, dipeptidylpeptidase 11, aspartic protease, cathepsin D, cysteine proteases such as calpain, CRES, cathepsins B, L, and S-like. Many of these enzymes are released during acrosome reaction when the outer acrosomal membrane and the overlapping sperm plasma membrane fuse, allowing the release of the acrosomal contents. In addition to the glycohydrolases and , proteinases the sperm acrosome contains esterases, sulfatases, phosphatases, and phospholipases. Some of these enzymes have been described in sufficient details elsewhere (Zaneveld and de Jonge, 1991), whereas phospholipases, metalloproteases, and ADAM proteins have been discussed in chapters 22,25 and 26 respectively. ACROSOME BIOGENESISThe acrosome of spermatowan is formed during spermiogenesis phase of spermatogenesis that lasts for about 20 days in rat. The Golgi apparatus is actively involved in the formation of sperm acrosome during Golgi phase and cap phase. During acrosome phase and maturation phase, the acrosomic system undergoes structural transformation and condensation, but without participation of Golgi apparatus. During Golgi phase, the proacrosomic granules appear as electron dense material and coalesce into larger proacrosomic granules (step 1-2).. . oligosaccharides on ZP3 that aggregate sperm-bound receptors, thus eliciting intracellular signals. On the sperm surface, it binds to terminal GlcNAc residues of 0-linked oligosaccharides of ZP3 perturbing GalTase or its ZP3 ligand affects sperm-zona binding (Gong et al., 1995). It seems that GalTase serves as a generalized gamete receptor in mammals. The PNA-positive glycoprotein of 135-150 kDa present on plasma me...

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“…Many glycosyltransferases, in their soluble forms, have been detected in testicular and epididymal fluid [4], ovarian follicular fluid [5] and uterine and oviductal fluid [6], and it has been suggested that they are involved in mammalian f e r t i l i z a t i o n [ 7 ] .…”

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N-acetylglucosaminyltransferase I Activity of Bovine Oviduct Epithelial Cells: Stimulation by Luteinizing Hormone, Vascular Endothelial Growth Factor and Tumor Necrosis Factor .ALPHA.

Nozaki

Wijayagunawardane

Kodituwakku

et al. 2005

Journal of Reproduction and Development

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Are there two forms of β2-N-acetylglucosaminyltransferase I in rat testicular and epididymal fluids?

Cited by 4 publications

References 26 publications

N-Acetylglucosaminyltransferase I Activity in Bovine Ovarian Follicular Fluids from Dominant and Atretic Follicles

N-Acetylglucosaminyltransferase I Activity in Bovine Ovarian Follicular Fluids from Dominant and Atretic Follicles

Acrosomal Enzymes

N-acetylglucosaminyltransferase I Activity of Bovine Oviduct Epithelial Cells: Stimulation by Luteinizing Hormone, Vascular Endothelial Growth Factor and Tumor Necrosis Factor .ALPHA.

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