Isoform Delta 4 of Calcium/calmodulin-dependent protein kinase type II subunit delta

CAMK2D encodes calcium/calmodulin-dependent protein kinase type II subunit delta, a serine/threonine kinase that plays a central role in calcium-dependent signaling and synaptic plasticity (UniProt: Q13557-4). The protein functions in neuronal signal transduction, where it couples calcium influx to phosphorylation of downstream substrates involved in synaptic transmission and long-term potentiation. This isoform (Delta 4) is a 519-amino acid variant of the full-length kinase.

CAMK2D is expressed primarily in the brain and is integral to excitatory neurotransmission and learning-related processes. The kinase is known to regulate AMPA and NMDA receptor trafficking and interacts with scaffold proteins at the postsynaptic density.

This CAMK2D isoform is downregulated in Alzheimer's Disease brain tissue (Chaparral AD proteomics). Analysis of post-mortem AD brain compared to age-matched controls using subcellular fractionation and mass spectrometry detected a mean log2 fold-change of −0.65, indicating reduced expression of this calcium signaling component in AD pathology. Reduced CAMK2D expression may contribute to synaptic dysfunction and impaired plasticity observed in neurodegeneration.