Linked Life Data

9804860

Source:http://linkedlifedata.com/resource/pubmed/id/9804860

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
1998-12-8
pubmed:abstractText
The equilibrative nucleoside transporters (ENTs) are a newly recognized family of membrane proteins of which hENT1 is the nitrobenzylmercaptopurine ribonucleoside (NBMPR)-sensitive (es) and hENT2 the NBMPR-insensitive (ei) transporter of human cells. BeWo cells exhibit large numbers (>10(7)/cell) of NBMPR-binding sites and high es and ei nucleoside transport activities relative to other cell types. In this work, we have demonstrated that proliferating BeWo cells possess (i) mRNA encoding hENT1 and hENT2 and (ii) hENT1-specific immunoepitopes. We examined NBMPR binding and its inhibition of uridine transport in various BeWo membrane fractions and proteoliposomes derived therefrom to determine if NBMPR binding to intracellular membranes represented interaction with functional es transporters. Unfractionated membranes and fractions enriched 5-fold in plasma membranes relative to postnuclear supernatants exhibited high NBMPR binding activity. Intact nuclei and nuclear envelopes also exhibited abundant quantities of NBMPR-binding sites with affinities similar to those of enriched plasma membranes (Kd = 0.4-0.9 nM). When proteoliposomes were made from octyl glucoside-solubilized membranes, high affinity NBMPR-binding sites were not only observed in crude membrane preparations and plasma membrane-enriched fractions but also in nuclear envelope fractions. Proteoliposomes prepared from either unfractionated membranes or nuclear envelopes exhibited both hENT1-mediated (82-85%) and hENT2-mediated (15-18%) transport of [3H]uridine. These results provided evidence for the presence of functional es and ei transporters in nuclear membranes and endoplasmic reticulum, suggesting that hENT1 and hENT2 may function in the translocation of nucleosides between the cytosol and the luminal compartments of one or both of these membrane types.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/4-nitrobenzylthioinosine, http://linkedlifedata.com/resource/pubmed/chemical/Affinity Labels, http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Equilibrative Nucleoside..., http://linkedlifedata.com/resource/pubmed/chemical/Equilibrative-Nucleoside..., http://linkedlifedata.com/resource/pubmed/chemical/Membrane Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Proteolipids, http://linkedlifedata.com/resource/pubmed/chemical/RNA, Messenger, http://linkedlifedata.com/resource/pubmed/chemical/SLC29A1 protein, human, http://linkedlifedata.com/resource/pubmed/chemical/SLC29A2 protein, human, http://linkedlifedata.com/resource/pubmed/chemical/Thioinosine, http://linkedlifedata.com/resource/pubmed/chemical/Uridine, http://linkedlifedata.com/resource/pubmed/chemical/proteoliposomes
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
30818-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Demonstration of equilibrative nucleoside transporters (hENT1 and hENT2) in nuclear envelopes of cultured human choriocarcinoma (BeWo) cells by functional reconstitution in proteoliposomes.
pubmed:affiliation
Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't