Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:4.6.1.2 (
guanylate cyclase
)
8,497
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The heme-regulated eukaryotic initiation factor 2alpha (eIF2alpha) kinase (
HRI
), which is found primarily in reticulocytes, contains an N-terminal heme-binding domain (NT-HBD). Binding of NO to the heme iron of the NT-HBD of
HRI
activates its eIF2alpha kinase activity, thus inhibiting the initiation of translation in reticulocyte lysate. The EPR spectrum of the NO-bound NT-HBD showed several derivative-shaped lines around g = 2.00, which is one of the well-documented signature patterns of a six-coordinate NO complex with histidine as the axial ligand. This is in sharp contrast to that of another prototypical NO-sensor protein, soluble
guanylate cyclase
(sGC), in which the NO binding to the heme iron disrupts the iron-histidyl bond forming a five-coordinate NO. The NO-mediated activation of
HRI
is, therefore, not triggered by the cleavage of the iron-histidyl bond. As evidenced by the resonance Raman spectra, two inactive forms of
HRI
, the ferrous ligand-unbound and the CO-bound states of the NT-HBD, contain a six-coordinate complex as found for the NO complex, indicating that the replacement of the sixth ligand of the heme iron is not sufficient to trigger the activation of
HRI
. Because the configuration of liganded NO is different from that of liganded CO, we propose that specific interactions between liganded NO and surrounding amino acid residues, which would not be formed in the CO complex, are responsible for the NO-induced activation of
HRI
.
...
PMID:NO-induced activation mechanism of the heme-regulated eIF2alpha kinase. 1243 Oct 98
