Heterogeneity of cAMP effect on endosomal proton transport
1Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550.
Abstract:
The effects of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) on proton transport in endocytotic vesicles (i.e., endosomes) obtained from rabbit renal cortex were investigated. Endosomes were prepared from New Zealand White rabbits following the intravenous injection of horseradish peroxidase. Under high (106 mM) chloride conditions, 5 microM 8-BrcAMP stimulated proton transport by 11 and 12% in fractions 1 and 2, but inhibited proton transport by 10, 8, and 14% in fractions 4, 5, and 6. Two hundred and fifty micromolar 8-BrcAMP inhibited proton transport progressively from 20% in fraction 1 to 50% in fraction 6. Under conditions in which chloride entry was minimized, i.e., low (6 mM) external chloride concentration plus voltage clamping, 5 microM 8-BrcAMP consistently and significantly inhibited proton transport by 40-60% in all six fractions. Under the same low chloride conditions, 250 microM 8-BrcAMP inhibited proton transport by 80-90% in all six fractions. These studies indicate that 8-BrcAMP can modify endosomal transport in a heterogeneous manner, that 8-BrcAMP inhibits the H+-ATPase directly, and that this effect is significantly modified by chloride. Last, these studies suggest that the observed heterogeneity in proton transport arises from interaction of 8-BrcAMP and chloride.
More Related Videos
07:38Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane
Published on: March 30, 2015
10:21Quantifying Spatiotemporal Parameters of Cellular Exocytosis in Micropatterned Cells
Published on: September 16, 2020
Related Concept Videos
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 are...
The Early Endosome: Endocytosis of Transferrin
Maturation of Endosomes
Changes in location
The maturing endosome moves along microtubules from the periphery of the cell towards the perinuclear region. This movement of the...
Energy to Drive Translocation
Generally, polypeptides are unfolded by two distinct...
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...
Transport Across the Golgi
