scholarly journals Rat mammary-gland transferrin: nucleotide sequence, phylogenetic analysis and glycan structure

1995 ◽  
Vol 307 (1) ◽  
pp. 47-55 ◽  
Author(s):  
H Escrivá ◽  
A Pierce ◽  
B Coddeville ◽  
F González ◽  
M Benaissa ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Mammary Gland ◽  
Sialic Acid ◽  
Amino Acid ◽  
Signal Sequence ◽  
Glycosylation Site ◽  
Glycan Structure ◽  
Sialic Acid Content ◽  
Native Page ◽  
Rat Mammary Gland

The complete cDNA for rat mammary-gland transferrin (Tf) has been sequenced and also the native protein isolated from milk in order to analyse the structure of the main glycan variants present. A lactating-rat mammary-gland cDNA library in lambda gt10 was screened with a partial cDNA copy of rat liver Tf and subsequently rescreened with 5′ fragments of the longest clones. This produced a 2275 bp insert coding for an open reading frame of 695 amino acid residues. This includes a 19-amino acid signal sequence and the mature protein containing 676 amino acids and one N-glycosylation site in the C-terminal domain at residue 490. Phylogenetic analysis was carried out using 14 translated Tf nucleotide sequences, and the derived evolutionary tree shows that at least three gene duplication events have occurred during Tf evolution, one of which generated the N- and C-terminal domains and occurred before separation of arthropods and chordates. The two halves of human melanotransferrin are more similar to each other than to any other sequence, which contrasts with the pattern shown by the remaining sequences. Native rat milk Tf is separated into four bands on native PAGE that differ only in their sialic acid content: one biantennary glycan is present containing either no sialic acid residues or up to three. The complete structures of the two major variants were determined by methylation, m.s. and 400 MHz 1H-n.m.r. spectroscopy. They contain either one or two neuraminic acid residues (alpha 2-->6)-linked to galactose in conventional biantennary N-acetyl-lactosamine-type glycans. Most contain fucose (alpha 1-->6)-linked to the terminal non-reducing N-acetylglucosamine.

THE EFFECTS OF SIALIDASE ON PSEUDOCHOLINESTERASE TYPES

1963 ◽  
Vol 41 (1) ◽  
pp. 969-974 ◽  
Author(s):  
D. J. Ecobichon ◽  
W. Kalow
Keyword(s):  
Sialic Acid ◽  
Amino Acid ◽  
Human Serum ◽  
Acid Content ◽  
Protein Molecule ◽  
Serum Cholinesterase ◽  
Kinetic Properties ◽  
Sialic Acid Content ◽  
Starch Gel ◽  
A Charge

Hereditary variants of human serum cholinesterase were exposed to the action of sialidase. The removal of the sialic acid residues had no effect on the kinetic properties of the esterases but greatly affected the electrophoretic mobility. In starch gel, there were no differences between the pseudocholinesterase types whether sialidase-treated or untreated. This observation permits two conclusions: first, the differences between the esterase types must reside in the protein cores, and second, the different variants must possess equal amounts of sialic acid per protein molecule. According to Liddell et al. there is a charge difference between esterase molecules of different type; since this cannot be accounted for by sialic acid content, the distinguishing characteristics are likely due to differences of amino acid composition.

Characterization and regulation of the gene expression of amino acid transport system A (SNAT2) in rat mammary gland

2006 ◽  
Vol 291 (5) ◽  
pp. E1059-E1066 ◽  
Author(s):  
Adriana López ◽  
Nimbe Torres ◽  
Victor Ortiz ◽  
Gabriela Alemán ◽  
Rogelio Hernández-Pando ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Transport System ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
Amino Acid Transport System ◽  
System A ◽  
Rat Mammary Gland

Amino acid transport via system A plays an important role during lactation, promoting the uptake of small neutral amino acids, mainly alanine and glutamine. However, the regulation of gene expression of system A [sodium-coupled neutral amino acid transporter (SNAT)2] in mammary gland has not been studied. The aim of the present work was to understand the possible mechanisms of regulation of SNAT2 in the rat mammary gland. Incubation of gland explants in amino acid-free medium induced the expression of SNAT2, and this response was repressed by the presence of small neutral amino acids or by actinomycin D but not by large neutral or cationic amino acids. The half-life of SNAT2 mRNA was 67 min, indicating a rapid turnover. In addition, SNAT2 expression in the mammary gland was induced by forskolin and PMA, inducers of PKA and PKC signaling pathways, respectively. Inhibitors of PKA and PKC pathways partially prevented the upregulation of SNAT2 mRNA during adaptive regulation. Interestingly, SNAT2 mRNA was induced during pregnancy and to a lesser extent at peak lactation. β-Estradiol stimulated the expression of SNAT2 in mammary gland explants; this stimulation was prevented by the estrogen receptor inhibitor ICI-182780. Our findings clearly demonstrated that the SNAT2 gene is regulated by multiple pathways, indicating that the expression of this amino acid transport system is tightly controlled due to its importance for the mammary gland during pregnancy and lactation to prepare the gland for the transport of amino acids during lactation.

THE EFFECTS OF SIALIDASE ON PSEUDOCHOLINESTERASE TYPES

1963 ◽  
Vol 41 (4) ◽  
pp. 969-974 ◽  
Author(s):  
D. J. Ecobichon ◽  
W. Kalow
Keyword(s):  
Sialic Acid ◽  
Amino Acid ◽  
Human Serum ◽  
Acid Content ◽  
Protein Molecule ◽  
Serum Cholinesterase ◽  
Kinetic Properties ◽  
Sialic Acid Content ◽  
Starch Gel ◽  
A Charge

Hereditary variants of human serum cholinesterase were exposed to the action of sialidase. The removal of the sialic acid residues had no effect on the kinetic properties of the esterases but greatly affected the electrophoretic mobility. In starch gel, there were no differences between the pseudocholinesterase types whether sialidase-treated or untreated. This observation permits two conclusions: first, the differences between the esterase types must reside in the protein cores, and second, the different variants must possess equal amounts of sialic acid per protein molecule. According to Liddell et al. there is a charge difference between esterase molecules of different type; since this cannot be accounted for by sialic acid content, the distinguishing characteristics are likely due to differences of amino acid composition.

scholarly journals The sialic acid content and isoelectric point of human kininogen

1975 ◽  
Vol 145 (2) ◽  
pp. 401-403 ◽  
Author(s):  
J C Londesborough ◽  
U Hamberg
Keyword(s):  
Molecular Weight ◽  
Sialic Acid ◽  
Amino Acid ◽  
Isoelectric Point ◽  
Acid Content ◽  
Low Molecular Weight ◽  
Sialic Acid Content

The sialic acid content of highly purified human kininogen was found to be about 8.6 mol/mol(mol.wt. 50,000). The isoelectric point (pH 4.9 +/- 0.2) is much higher than that of bovine low-molecular-weight kininogen, but is close to that expected from the amino acid and sialic acid analyses.

scholarly journals Molecular-scale features that govern the effects of O-glycosylation on a carbohydrate-binding module

2015 ◽  
Vol 6 (12) ◽  
pp. 7185-7189 ◽  
Author(s):  
Xiaoyang Guan ◽  
Patrick K. Chaffey ◽  
Chen Zeng ◽  
Eric R. Greene ◽  
Liqun Chen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Glycosylation Site ◽  
Glycan Structure ◽  
Carbohydrate Binding ◽  
Carbohydrate Binding Module ◽  
Amino Acid Residues ◽  
Glycosidic Linkage ◽  
Molecular Scale

The importance of the glycan structure and size, amino acid residues near the glycosylation site, and glycosidic linkage in controlling the effects of CBMO-glycosylation is shown.

scholarly journals The isolation of ovomucoid variants differing in carbohydrate composition

1971 ◽  
Vol 123 (3) ◽  
pp. 399-405 ◽  
Author(s):  
J. G. Beeley
Keyword(s):  
Sialic Acid ◽  
Amino Acid ◽  
Acid Content ◽  
Deae Cellulose ◽  
Structure And Function ◽  
Inhibiting Activity ◽  
Carbohydrate Composition ◽  
Charge Heterogeneity ◽  
Sialic Acid Content ◽  
And Function

Three major and two minor species of ovomucoid were separated by chromatography on sulphoethyl-Sephadex. The predominant sialic acid-free species was further resolved into three fractions by DEAE-cellulose chromatography. Although all species of ovomucoid had closely similar trypsin-inhibiting activity, immunochemical properties and amino acid composition, they differ in carbohydrate composition. Wide variation was observed in the content of galactose, N-acetylglucosamine and sialic acid. Charge heterogeneity was related, in part, to variation in sialic acid content. The implications of variable carbohydrate composition for the structure and function of ovomucoid are discussed.

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