Linked Life Data

14520572

Source:http://linkedlifedata.com/resource/pubmed/id/14520572

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2003-10-1
pubmed:abstractText
Adenosine diphosphate glucose pyrophosphorylase (AGPase; EC 2.7.7.27) synthesizes the starch precursor, ADP-glucose. It is a rate-limiting enzyme in starch biosynthesis and its activation by 3-phosphoglyceric acid (3PGA) and/or inhibition by inorganic phosphate (Pi) are believed to be physiologically important. Leaf, tuber and cereal embryo AGPases are highly sensitive to these effectors, whereas endosperm AGPases are much less responsive. Two hypotheses can explain the 3PGA activation differences. Compared to leaf AGPases, endosperm AGPases (i) lack the marked ability to be activated by 3PGA or (ii) they are less dependent on 3PGA for activity. The absence of purified preparations has heretofore negated answering this question. To resolve this issue, heterotetrameric maize ( Zea mays L.) endosperm and potato ( Solanum tuberosum L.) tuber AGPases expressed in Escherichia coli were isolated and the relative amounts of enzyme protein were measured by reaction to antibodies against a motif resident in both small subunits. Resulting reaction rates of both AGPases are comparable in the presence but not in the absence of 3PGA when expressed on an active-protein basis. We also placed the potato tuber UpReg1 mutation into the maize AGPase. This mutation greatly enhances 3PGA sensitivity of the potato AGPase but it has little effect on the maize AGPase. Thirdly, lysines known to bind 3PGA in potato tuber AGPase, but missing from the maize endosperm AGPase, were introduced into the maize enzyme. These had minimal effect on maize endosperm activity. In conclusion, the maize endosperm AGPase is not nearly as dependent on 3PGA for activity as is the potato tuber AGPase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0032-0935
pubmed:author
pubmed:issnType
Print
pubmed:volume
217
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
449-56
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Relative turnover numbers of maize endosperm and potato tuber ADP-glucose pyrophosphorylases in the absence and presence of 3-phosphoglyceric acid.
pubmed:affiliation
Program in Plant Molecular and Cellular Biology, Horticultural Sciences, University of Florida, Gainesville 32611, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't