Linked Life Data

8489255

Source:http://linkedlifedata.com/resource/pubmed/id/8489255

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1993-6-10
pubmed:abstractText
There are well-established differences in the expression of neolacto neutral glycosphingolipids among human leukocyte subclasses. Mature myeloid cells express several types of these compounds, whereas mature lymphoid cells are deficient in such compounds. The biochemical basis for this is unknown. Therefore, enzyme studies were done to determine whether different classes of leukocytes (represented by cell lines) contained beta 1-3-N-acetylglucosaminyltransferase activity (EC 2.4.1.149, beta 1-3GlcNAcT(i)). This enzyme participates in the synthesis of Type 2 chains in glycosphingolipids by catalyzing the following two reactions: (i) Gal beta 1-4Glc beta 1-1Cer (lactosylceramide, LacCer) + UDP-GlcNAc-->GlcNAc beta 1-3Gal beta 1-4Glc beta 1- 1Cer (lactotriaosylceramide) and (ii) Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer (neolactotetraosylceramide) + UDP-GlcNAc-->GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer. The first reaction may be the key step in the biosynthetic pathway of neolacto structures in human leukocytes. Therefore, extracts from several cell lines representative of both myeloid and lymphoid lineages, at varied stages of maturity, were assayed with LacCer for the presence of beta 1-3GlcNAcT(i) activity. Our results indicate that myeloid cells contain this initiating beta 1-3GlcNAcT(i) activity, whereas lymphoid cells do not. This is consistent with our thin-layer chromatography immunostain results which show that all myeloid cell lines express neutral neolacto glycosphingolipids and lymphoid cells do not. Our findings suggest that the presence of the initiating activity only in myeloid cells is a regulatory factor in the expression of neutral neolacto glycosphingolipids in human leukocytes. We also tested both myeloid and lymphoid cell lines for the presence of elongating beta 1-3GlcNAcT(i) activity (reaction (ii) above) by using neolactotetraosylceramide as an acceptor. Our results show that an elongating activity is expressed by all myeloid and lymphoid cell lines tested. Initiating (myeloid) and elongating (myeloid and lymphoid) activities were distinguished by several characteristics: metal ion activation, pH optimum, and kinetic constants. In conclusion, our results indicate the presence of two beta 1-3GlcNAcT(i) activities in human leukocytes: one that catalyzes the initial reaction and is found only in the myeloid lineage and one that catalyzes the elongating reaction and is found in both myeloid and lymphoid cells.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0003-9861
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
303
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
125-33
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Beta 1-3-N-acetylglucosaminyltransferase in human leukocytes: properties and role in regulating neolacto glycosphingolipid biosynthesis.
pubmed:affiliation
Department of Chemistry and Biochemistry, San Francisco State University, California 94132.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.