Neurogranin is a calmodulin-binding protein expressed primarily in the brain, particularly in dendritic spines, and participating in the protein kinase C signaling pathway. Neurogranin is the main postsynaptic protein regulating the availability of calmodulin, binding to it in the absence of calcium. Phosphorylation by protein kinase C lowers its binding ability. NRGN gene expression is controlled by thyroid hormones.[3] Human neurogranin consists of 78 amino acids.
One study tells of potential link of neurogranin gene to the heightened risk of schizophrenia in males,[4] another study gives evidence of lowered neurogranin immunoreactivity in the brains of people suffering from schizophrenia.[5]
Neurogranin concentration in cerebrospinal fluid (CSF) is further discussed as marker for synaptic dysfunction in age-related neurodegeneration.[6] It has also been shown to be specifically increased in patients with Alzheimer's disease.[7][8] Especially the ratio of CSF neurogranin trunc P75 and the beta-secretase BACE1 is suggested as potential marker for cognitive deterioration in the progress of Alzheimer's disease.[9]
Prior to its identification in the bovine and rat brain in 1991,[10] neurogranin was known as a putative protein kinase C-phosphorylated protein named p17. Human neurogranin was cloned in 1997 and turned out to be 96% identical to the rat protein.[11]
