Apr 1, 1974

Light-dependent redistribution of ions in suspensions of chloroplast thylakoid membranes

Proceedings of the National Academy of Sciences of the United States of America
G HindS Izawa


Ion movements associated with the pH rise that is observed upon illumination of thylakoid suspensions at low pH have been studied by a multiparameter technique. Light-dependent, dark-reversible fluxes of H(+), Cl(-), Na(+), K(+) and divalent cations were monitored, together with simultaneous changes in the optical density of the suspension. Extensive uptake of Cl(-) and efflux of Mg(2+) accompany the apparent inward movement of H(+) in the light. Only minor efflux of K(+) is seen and Na(+) appears immobile. The Cl(-) and Mg(2+) fluxes together compensate for most of the charge transferred as H(+), contributing respectively about 49% and 43% on an equivalent basis. The ratio of Cl(-) influx to Mg(2+) efflux is variable, but usually >1.0. The Mg(2+) flux can be supplanted by (1) K(+) flux, if the K(+)/Mg(2+) activity ratio in the suspension is high, and (2) Ca(2+) flux, if the thylakoids are equilibrated with suspending media containing Ca(2+). The affinity of the divalentcation-binding sites, or carrier mechanism, is greater for Ca(2+) than for Mg(2+). Schemes can be drawn up to account for the observed ion movements on the basis of either a chemical or a chemiosmotic mechanism for energy transduction in chloroplasts. In intact ...Continue Reading

  • References20
  • Citations101


Mentioned in this Paper

Chloride Ion Level
Chemiosmotic Mechanisms
Biochemical Pathway
Cations, Divalent
Tissue Membrane
Energy Transfer

About this Paper

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Bone Marrow Neoplasms

Bone Marrow Neoplasms are cancers that occur in the bone marrow. Discover the latest research on Bone Marrow Neoplasms here.

IGA Glomerulonephritis

IgA glomerulonephritis is a chronic form of glomerulonephritis characterized by deposits of predominantly Iimmunoglobin A in the mesangial area. Discover the latest research on IgA glomerulonephritis here.

Cryogenic Electron Microscopy

Cryogenic electron microscopy (Cryo-EM) allows the determination of biological macromolecules and their assemblies at a near-atomic resolution. Here is the latest research.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

LRRK2 & Immunity During Infection

Mutations in the LRRK2 gene are a risk-factor for developing Parkinson’s disease. However, LRRK2 has been shown to function as a central regulator of vesicular trafficking, infection, immunity, and inflammation. Here is the latest research on the role of this kinase on immunity during infection.

Antiphospholipid Syndrome

Antiphospholipid syndrome or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by the presence of antibodies directed against phospholipids.

Meningococcal Myelitis

Meningococcal myelitis is characterized by inflammation and myelin damage to the meninges and spinal cord. Discover the latest research on meningococcal myelitis here.

Alzheimer's Disease: MS4A

Variants within membrane-spanning 4-domains subfamily A (MS4A) gene cluster have recently been implicated in Alzheimer's disease by recent genome-wide association studies. Here is the latest research.