Plant Physiol, May 2001, Vol. 126, pp. 261-266
ADP-Glucose Pyrophosphorylase Is Located in the Plastid in
Developing Tomato Fruit1
Diane M.
Beckles,2
Josephine
Craig, and
Alison
M.
Smith*
John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom
(D.M.B., A.M.S.); and Zeneca Plant Sciences, Jealotts Hill Research
Station, Bracknell, Berks RG42, United Kingdom (J.C.)
The subcellular location of activity and protein of ADP-glucose
pyrophosphorylase (AGPase) in developing tomato (Lycopersicon esculentum) fruit was determined following a report that the
enzyme might be present inside and outside the plastids in this organ. Plastids prepared from crude homogenates of columella and pericarp, the
starch-accumulating tissues of developing fruit, contained 8% to 18%
of the total activity of enzymes known to be confined to plastids, and
0.2% to 0.5% of the total activity of enzymes known to be confined to
the cytosol. The proportion of the total activity of AGPase in the
plastids was the same as that of the enzymes known to be confined to
the plastid. When samples of plastid and total homogenate fractions
were subjected to immunoblotting with an antiserum raised to AGPase,
most or all of the protein detected was plastidial. Taken as a whole,
these data provide strong evidence that AGPase is confined to the
plastids in developing tomato fruit.
1
This work was supported by a Competitive
Strategic Grant from the Biotechnology and Biological Sciences Research
Council, and by the Commonwealth Scholarship Commission, the
Association of Commonwealth Universities, and the Cambridge
Philosophical Society (to D.M.B.).
2
Present address: Dupont Agricultural Products,
Experimental Station, P.O. Box 80402, Wilmington, DE
19880-0402.
*
Corresponding author; e-mail alison.smith{at}bbsrc.ac.uk; fax
44-1603-450045.
© 2001 American Society of Plant Physiologists
