Release-activated Ca2+ transport in neurons of frog sympathetic ganglia.
Frog sympathetic ganglion neurons exhibit a novel Ca2+ uptake mechanism, release-activated calcium transport or RACT, which is manifest in both cytosolic and store [Ca2+] signals as greatly accelerated Ca2+ uptake after Ca2+ release from internal stores. RACT is activated by Ca2+ release but not by Ca2+ entry and serves to selectively refill Ca2+ stores after release. RACT lowers cytosolic [Ca2+] with a rate constant about 1.6 times that of the SERCA pump with empty ER. RACT is thapsigargin-insensitive, was eliminated by ryanodine, but was not affected by blocking mitochondrial or plasma membrane Ca2+ transport. A Ca2+ flux model with RACT in the ER membrane reproduced the cytosolic and store [Ca2+] responses to all stimuli.
Cseresnyés
Z
Z
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
Bustamante
A I
AI
Klein
M G
MG
Schneider
M F
MF
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000378:metabolism*; D008959:Models, Neurological; D009474:Neurons / Q000378:metabolism*; D011893:Rana esculenta
D002118:Calcium