1. Regulation of linkages between the erythrocyte membrane and its skeleton by 2,3-diphosphoglycerate.
- Author
-
Moriyama R, Lombardo CR, Workman RF, and Low PS
- Subjects
- 2,3-Diphosphoglycerate, Ankyrins isolation & purification, Calorimetry, Differential Scanning, Erythrocyte Membrane drug effects, Humans, Kinetics, Membrane Proteins isolation & purification, Protein Binding, Ankyrins metabolism, Cytoskeletal Proteins, Diphosphoglyceric Acids pharmacology, Erythrocyte Membrane metabolism, Membrane Proteins metabolism, Neuropeptides
- Abstract
In addition to reducing hemoglobin-O2 affinity, 2,3-diphosphoglycerate (DPG) is known to modulate the mechanical properties of the erythrocyte membrane. By fluorescence spectroscopy and differential scanning calorimetry, we demonstrate that DPG binds the cytoplasmic domain of erythrocyte membrane band 3 in two stages characterized by apparent KD values of approximately approximately 2 and 12 mM. DPG was also shown to perturb the stability of ankyrin, protein 4.1, and protein 4.2 in situ and to directly bind to protein 4.1. In studies of membrane-skeleton interactions, DPG was observed to inhibit the fast and slow phases of ankyrin binding to band 3 and to reduce both the number of ankyrin sites and affinity of ankyrin for each class of site. The inhibition was biphasic, similar to the band 3-DPG binding isotherm; however, at physiological DPG concentrations a reduction in only 15% of the ankyrin sites was observed. In contrast, inhibition of protein 4.1 binding to the membrane reached 65% at physiological DPG concentrations (approximately approximately 5.9 mM); at more elevated concentrations, blockade was nearly quantitative, affecting glycophorin and band 3 sites alike. Taken together with previous observations, these data suggest that DPG's effect on O2 delivery may extend beyond its well recognized impact on hemoglobin-O2 affinity.
- Published
- 1993