Citrate transport in corn mitochondria

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.70.2.511· OSTI ID:5077906

Birnberg, P R; Jayroe, D L; Hanson, J B

Citrate uptake by corn mitochondria (Zea mays L. B73 x Mo19) was investigated by osmotic swelling and (/sup 14/C)citrate accumulation. Uptake driven by passive influx, ammonium gradients, and respiration was followed. There was no requirement for phosphate and/or malate to secure citrate uptake, although under some conditions these additives were promotive. Inhibition of the phosphate and dicarboxylate carriers did not eliminate citrate uptake. Citrate/sub in//malate/sub out/ exchange occurs, but at a rate too slow to account for observed citrate uptake, and depletion of endogenous malate only reduced citrate uptake by 38%. It was concluded that citrate can be rapidly accumulated by a mechanism other than by exchange for dicarboxylates. The effect of uncoupler on respiration-driven (/sup 14/C)citrate accumulation, and studies of passive swelling using ionophores and uncouplers indicated that the major avenue of citrate uptake is by H/sup +//citrate cotransport with a pH optimum near 4.5. The in vivo role of this mechanism is not yet understood.

• Research Organization: Univ. of Illinois, Urbana
• DOE Contract Number: AC02-76EV00790
• OSTI ID: 5077906
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 70; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CEREALS
CITRIC ACID
DATA
EXPERIMENTAL DATA
GRAMINEAE
GRASS
HYDROXY ACIDS
INFORMATION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAIZE
MITOCHONDRIA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
PH VALUE
PLANTS
REACTION KINETICS
TRACER TECHNIQUES
UPTAKE