Linked Life Data

3480519

Source:http://linkedlifedata.com/resource/pubmed/id/3480519

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
1988-2-20
pubmed:abstractText
In crude extracts of epidermal papillomas induced by an initiation-promotion protocol, ornithine decarboxylase (OrnDCase) activity was increased by the addition of GTP to the enzyme assay. No effect of GTP on the phorbol ester-induced enzyme isolated from normal epidermis was observed. Kinetic analyses indicated that the major effect of the nucleotide on the tumor-derived enzyme was to lower the apparent Km for L-ornithine. When papilloma OrnDCase was partially purified by gel-filtration chromatography, two forms of the enzyme were resolved, only one of which was found in an epidermal extract from phorbol 12-myristate 13-acetate-treated mice. The enzymatic properties of the two forms of papilloma enzyme were compared. The higher molecular weight form (peak I) was activated by GTP, while the lower molecular weight form (peak II) was not. As expected from the kinetic analyses of the crude papilloma extracts, the apparent Km of peak I enzyme for L-ornithine was very high (1.25 mM) but was much lower in the presence of GTP (0.02 mM). The two forms of papilloma OrnDCase differed in their sensitivities to heat inactivation and the ability of GTP to protect against heat inactivation. The K1/2 for activation of peak I OrnDCase by GTP was 0.1 microM. The activation process was irreversible and did not require Mg2+. When several nucleotides were tested for their ability to activate peak I OrnDCase, only GTP, dGTP, and the nonhydrolyzable derivative GTP[gamma-S] were effective, while GDP, GMP, ATP, and CTP were relatively ineffective. Our results demonstrated the existence of two forms of OrnDCase in epidermal tumor extracts, of which one can be activated by GTP and one cannot. The significance of these findings for the regulation of this enzyme in normal and tumor cells is discussed.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-1277170, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-2423265, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-3467314, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-3815331, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-4555250, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-48421, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-6321035, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-6582509, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-6587379, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-6800359, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-7083470, http://linkedlifedata.com/resource/pubmed/commentcorrection/3480519-908030
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0027-8424
pubmed:author
pubmed:issnType
Print
pubmed:volume
84
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8927-31
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Activation of mouse epidermal tumor ornithine decarboxylase by GTP: evidence for different catalytic forms of the enzyme.
pubmed:affiliation
Wistar Institute, Philadelphia, PA 19104.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.