Introduction of a phosphate at serine741 of the calmodulin-binding domain of the neuronal nitric oxide synthase (NOS-I) prevents binding of calmodulin.
The calmodulin-binding domain of neuronal nitric oxide synthase (NOS-I) is represented by a segment of 26 amino acids. We tested whether the phosphorylation of a serine in the calmodulin-binding domain changes the affinity of calmodulin for this binding site. We monitored the binding of calmodulin to synthetic peptides by surface plasmon resonance spectroscopy, an electrophoretic mobility assay, circular dichroism spectroscopy and competitive inhibitory studies. All four experimental approaches showed that binding of calmodulin to the calmodulin-binding site is blocked by introduction of a phosphate. Phosphorylation of the calmodulin-binding domain of NOS-I could be a negative feedback loop to turn off NOS-I activity.
PubMed Abstracts
PubMed Abstracts