Related Experiment Video
Updated: May 3, 2026

Collection and Analysis of Arabidopsis Phloem Exudates Using the EDTA-facilitated Method
Published on: October 23, 2013
Adenosine triphosphatase in the phloem of Cucurbita
1Department of Biological Sciences, University of California, 93106, Santa Barbara, California, USA.
Abstract:
The distribution of adenosine triphosphatase (ATPase) activity in the phloem of petioles and minor veins of Cucurbita maxima has been studied using a lead phosphate precipitation procedure. ATPase activity was localized in sieve elements, companion cells and parenchyma cells. Activity was found at the cell surfaces, associated with the dispersed P-protein of mature sieve elements, in mitochondria, sieve-element reticulum, and at specific regions of the cell walls. It is suggested that the ATPase at the phloem cell surfaces may function in intercellular transport of assimilates or ions, and that the ATPase activity associated with the P-protein may function in the translocation process or in callose deposition.
Related Concept Videos
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
ATP Driven Pumps I: An Overview
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and...
ATP Driven Pumps III: V-type Pumps
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
Transducer Mechanism: Enzyme-Linked Receptors
Major types that are helpful drug targets include:
ATP Energy Storage and Release
One example of energy coupling using ATP involves a...
C4 Pathway and CAM
C4 Pathway
The C4 pathway is used by plants such as...

