Linked Life Data

6725281

Source:http://linkedlifedata.com/resource/pubmed/id/6725281

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1984-7-16
pubmed:abstractText
GDP regulation of basal and receptor-mediated catecholamine-sensitive human fat cell adenylate cyclase was studied using purified plasma membrane preparations and assay conditions selected to minimize conversion of GDP to GTP. Under ordinary assay conditions (low NaCl concentration) and with App(NH)p as substrate to prevent GDP conversion to GTP, basal enzyme activity was stimulated up to 2-fold by GDP (0.1 mM) while addition of epinephrine (0.1 mM) eliminated stimulation by GDP and reduced basal adenylate cyclase activity. With ATP as substrate, the enzyme was not responsive to hormone in the absence of guanyl nucleotides and GDP augmentation of basal activity was small (0-1.5-fold) while stimulatory effects of epinephrine and isoproterenol were minimally but definitely exhibited (1.5-fold over basal). Guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), a GDP analog resistant to phosphorylation and hydrolysis and an antagonist of GTP, stimulated enzyme activity more than did GDP but did not promote epinephrine action. Rather, inhibition of GDP beta S-stimulated adenylate cyclase activity was seen with both epinephrine and isoproterenol and also with GTP. In the presence of NaCl (200 mM), which alone produced 2-3-fold increase in basal enzyme activity, GDP (0.1 mM) and GDP beta S (50 microM) produced 8- and 15-fold increases of activity, respectively. Addition of UDP, to prevent possible conversion of GDP to GTP, had no effect on NaCl-enhanced activation by GDP. The results indicate that the human fat cell adenylate cyclase system is unique in responding to GDP and its analog GDP beta S by stimulation in the absence of hormone but suggest that as in other systems catecholamine-mediated stimulation is normally dependent on GTP. Salts (Na+) appear to stimulate the enzyme by facilitating the interaction of the guanyl nucleotide regulatory protein (N8) with the catalytic unit.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Adenylate Cyclase, http://linkedlifedata.com/resource/pubmed/chemical/Adenylyl Imidodiphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Epinephrine, http://linkedlifedata.com/resource/pubmed/chemical/Guanine Nucleotides, http://linkedlifedata.com/resource/pubmed/chemical/Guanosine Diphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Guanosine Triphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Guanylyl Imidodiphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Thionucleotides, http://linkedlifedata.com/resource/pubmed/chemical/Uridine Diphosphate, http://linkedlifedata.com/resource/pubmed/chemical/guanosine 5'-O-(2-thiodiphosphate)
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
259
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7038-44
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Stimulation of human fat cell adenylate cyclase by GDP and guanosine 5'-O-(2-thiodiphosphate).
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't