Gravity sensing takes place in the columella cells of the root cap, where sedimentation of starch-filled plastids (amyloplasts) triggers a pathway that results in a relocalization to the lower side of the cell of PIN proteins, which facilitate efflux of the plant hormone auxin efflux.
These cells hyper-accumulate copper as the truncated ATP7A protein is unable to facilitate efflux of excess copper and the ATP7B efflux protein is not expressed.
One potential candidate is Ant1, a mitochondrial ATP/ADP exchanger that facilitates efflux of ATP out of the mitochondria and glutamate uptake into astrocytes [ 256].
Along with its role in drug resistance, MRP1 also facilitates efflux of antioxidant glutathione and the proinflammatory leukotriene C4 (142) as well as E1S (143) and DHEAS (144), and is expressed in a range of cancerous tissues including hormone-dependent breast (145), prostate (146), and colorectal cancer (147).
Efflux transporters mechanistically limit the enterocytic levels of their respective substrates by reducing uptake and facilitating efflux, whereas SLC transporters which include peptide transporter (PepTI) and organic anion polypeptide transporter (OATP1A2) amongst others are secondary active transporters that employ energy coupling mechanisms [ 29, 30].
Such information should also aid the discovery and development of drugs which facilitate efflux transport of GCs at the BBB and the BCSFB in order to prevent accumulation of GCs, as well as drugs which facilitate the influx transport of CT at the BBB to promote efficient supplementation of CT.
36, 37 Emergency mechanisms, such as reduced uptake, facilitated efflux, sequestration, and modification, are commonly utilized by organisms to achieve resistance to the toxicity of heavy metals.
All these genes encode membrane proteins, consistent with their role in facilitating the efflux of organic acid anions.
Cellular Na overload and AP prolongation stimulate the reverse mode NCX facilitating the efflux of Na in exchange for influx of Ca [ 14].
Previous studies have shown that a decrease in blood glutamate concentration leads to a larger natural glutamate gradient between the brain and blood, facilitating the efflux of excess extracellular brain glutamate into the blood.
