Linked Life Data

8144614

Source:http://linkedlifedata.com/resource/pubmed/id/8144614

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
1994-5-5
pubmed:abstractText
The developmental expression of the alpha 2,6- and alpha 2,8-linked sialic acid (Sia) residues in trout egg polysialoglycoproteins (PSGPs) was studied by correlating the temporal expression of these sugar residues, and the prerequisite sialyltransferases responsible for their synthesis, during oogenesis. The following new findings are reported. 1) Disialylated glycoproteins were identified in ovaries 4-6 months prior to ovulation. Three months prior to ovulation, a second more highly sialylated glycoprotein appeared. Structural studies confirmed that the two glycoproteins were discrete molecular species, designated PSGP(low Sia) and PSGP(high Sia), which differed only in their Sia content. PSGP(low Sia) contained mostly disialyl (Sia alpha 2,8-Sia alpha 2,6-) side chains, whereas PSGP(high Sia) contained alpha 2,8-linked oligo/polySia side chains ranging in length from 2 to over 20 Sia residues. The average degree of polymerization ([DP]av) was 6. 2) Biosynthetic studies using CMP-[14C]Neu5Ac indicated that three sialyltransferase activities were responsible for synthesis of the polysialyl residues of PSGPs: (i) alpha-N-acetylgalactosaminide alpha 2,6-sialyltransferase (alpha 2,6-ST), which catalyzed formation of the Sia residues alpha 2,6-linked to the proximal GalNAc residues in asialo-PSGP; (ii) alpha 2,6-sialoside alpha 2,8-sialyltransferase (alpha 2,8-ST or "initiase"), which catalyzed transfer of the first alpha 2,8-Sia residue to the alpha 2,6-linked Sia residue; and (iii) an alpha 2,8-polysialyltransferase (alpha 2,8-polyST or "polymerase"), responsible for synthesis of the alpha 2,8-linked poly/oligo Sia chains in PSGP(high Sia). Expression of these enzyme activities increased in accordance with the developmental appearance of each PSGP. 3) Structural characterization of the [14C]Sia-labeled side chains of each PSGP at different stages of development confirmed that synthesis of the disialyl unit containing a single alpha 2,8-Sia residue occurred before alpha 2,8-polysialylation. 4) In ovaries, 96% of the sialyltransferase activities were found in the Golgi-derived immature cortical vesicles or as soluble enzymes released from the fragile vesicles. Less than 4% of the activities were localized in the membrane (Golgi) fraction. In mature eggs, the sialyltransferases were also detected as soluble enzymes, and within the cortical vesicles.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
269
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10330-40
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Developmental expression of trout egg polysialoglycoproteins and the prerequisite alpha 2,6-, and alpha 2,8-sialyl and alpha 2,8-polysialyltransferase activities required for their synthesis during oogenesis.
pubmed:affiliation
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't