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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:dateCreated |
1989-8-25
|
| pubmed:abstractText |
Dictyostelium discoideum cells contain a ras gene that codes for a polypeptide that is highly homologous to the human ras proteins. Extra copies of the wild-type gene or a gene carrying a missense mutation in codon 12 (ras-Gly12 and ras-Thr12, respectively) have been introduced into Dictyostelium cells by transformation. We have investigated the properties of the chemotactic cell surface cyclic AMP receptor in crude membrane preparations of wild-type Dictyostelium cells and ras-Gly12 and ras-Thr12 transformants. In vitro, an ATP- and Ca2+-dependent reduction of the number of cyclic AMP receptors was observed in membranes from all three cell types. The number of available receptors was decreased maximally by about 50%. In the presence of ATP the half-maximal Ca2+ concentration required for this process was about 10(-5) M in wild-type and ras-Gly12 membranes, and less than 10(-7) M in ras-Thr12 membranes. Addition of GTP (but not GDP) or the phorbol ester PMA (phorbol-12-myristate-13-acetate) reduced the Ca2+ requirement of the process in wild-type and ras-Gly12 membranes to the physiological level of less than 10(-7) M. In membranes derived from ras-Thr12 cells addition of GTP or PMA had no effect. The results indicate that D. discoideum cells contain a cyclic AMP receptor-controlling pathway that can be activated in vitro and involves a GTP-binding protein and a Ca2+ plus ATP-dependent activity, possibly protein kinase C. It is concluded that the ras protein specifically interacts with this pathway; the pathway appears to be constitutively activated by the mutated ras gene product.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Aug
|
| pubmed:issn |
0021-9533
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| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
90 ( Pt 4)
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
701-6
|
| pubmed:dateRevised |
2003-11-14
|
| pubmed:meshHeading |
pubmed-meshheading:2855334-Animals,
pubmed-meshheading:2855334-Cell Membrane,
pubmed-meshheading:2855334-Chemotaxis,
pubmed-meshheading:2855334-Cyclic AMP,
pubmed-meshheading:2855334-Dictyostelium,
pubmed-meshheading:2855334-Genes, ras,
pubmed-meshheading:2855334-Mutation,
pubmed-meshheading:2855334-Receptors, Cyclic AMP
|
| pubmed:year |
1988
|
| pubmed:articleTitle |
Expression of a mutated ras gene in Dictyostelium discoideum alters the binding of cyclic AMP to its chemotactic receptor.
|
| pubmed:affiliation |
Laboratory of Biochemistry, University of Amsterdam, The Netherlands.
|
| pubmed:publicationType |
Journal Article
|