Ca2+ release from endoplasmic reticulum is mediated by a guanine nucleotide regulatory mechanism.
Ca2+ accumulation and release from intracellular organelles is important for Ca2+-signalling events within cells. In a variety of cell types, the active Ca2+-pumping properties of endoplasmic reticulum (ER) have been directly studied using chemically permeabilized cells. The same preparations have been extensively used to study Ca2+ release from ER, in particular, release mediated by the intracellular messenger inositol 1,4,5-trisphosphate (InsP3). So far, these studies and others using microsomal membrane fractions have revealed few mechanistic details of Ca2+ release from ER, although a recent report indicated that InsP3-mediated Ca2+ release from liver microsomes may be dependent on GTP. In contrast to the latter report, we describe here the direct activation of a specific and sensitive guanine nucleotide regulatory mechanism mediating a substantial release of Ca2+ from the ER of cells of the neuronal cell line N1E-115. These data indicate the operation of a major new Ca2+ gating mechanism in ER which is specifically activated by GTP, deactivated by GDP, and which appears to involve a GTP hydrolytic cycle.
D L
DL
Gill
T
T
Ueda
S H
SH
Chueh
M W
MW
Noel
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002451:Cell Compartmentation / Q000187:drug effects; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006153:Guanosine Diphosphate / Q000502:physiology; D006160:Guanosine Triphosphate / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology; D051379:Mice; D009447:Neuroblastoma
D007473:Ion Channels; D006153:Guanosine Diphosphate; D000001:Calcimycin; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D002118:Calcium