Neurogranin is a small, acidic protein that is highly expressed in the central nervous system, particularly in neurons. It plays a pivotal role in synaptic plasticity, which is fundamental for learning and memory processes. Located in the postsynaptic density of excitatory synapses, Neurogranin binds to calmodulin. This binding is calcium - dependent. When intracellular calcium levels rise in response to neuronal activity, calcium - calmodulin complexes form. Neurogranin's interaction with calmodulin then modulates the activity of protein kinase C (PKC), an enzyme involved in signal transduction pathways. By regulating PKC, Neurogranin influences the phosphorylation of various synaptic proteins. This, in turn, impacts the structure and function of synapses, allowing for the strengthening or weakening of synaptic connections, essential for encoding and retrieving information in the brain.