CAMK2B/A1851

CAMK2B, also known as A1851, is the beta subunit of the calcium/calmodulin-dependent protein kinase II (CaM kinase II).

CAMK2B, also known as A1851, is the beta subunit of the calcium/calmodulin-dependent protein kinase II (CaM kinase II). This protein is a heteromultimeric holoenzyme composed of 8 to 12 subunits: alpha, beta, gamma or delta in a variable ratio. The two main subunits in the brain are alpha and beta; these subunits form the holoenzymes that constitute 1–2% of total brain protein in rats. It is enriched at synapses and is the main protein of the post-synaptic density region. The catalytic activity of CAMK2B is triggered in a calcium-dependent manner, following auto-phosphorylation that becomes independent of calcium. CAMK2 translocates to synapses and binds directly to the N-methyl-D-aspartate (NMDA) receptor in response to calcium ion entry through this receptor. This protein regulates alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) properties and the synaptic incorporation of AMPARs in response to synaptic activity. Activity-dependent regulation of AMPAR levels in excitatory synapses is a critical mechanism for changing synaptic strength during NMDA receptor-dependent long-term potentiation (LTP). It has been reported that the activity changes the proportions of CAMK2A and CAMK2B subunits, the levels of CAML2A increased with heightened activity, and the levels of CAMK2B increased with suppression of activity. This change in the ratio may tune the CAMK2 holoenzyme to changing intensities of signaling.