Transmembrane AMPA receptor regulatory proteins (TARPs) serve as auxiliary subunits of AMPA receptors and regulate functional aspects of these receptors such as: fast excitatory synaptic transmission, surface trafficking, synaptic clustering and glutamate affinity. Generally, TARPs are responsible for regulating expression, channel properties and localization of AMPA receptors in the brain¹.

TARPs are non-pore-forming integral membrane proteins with four transmembrane domains that are widely expressed in the CNS. TARP family is divided in two: Type I and type II. Type I TARPs include two calcium channel γ subunits: γ5 and γ7, also known as Cacng5 and Cacng7, respectively.They do not traffic AMPAR, they only modulate existing AMPAR channel function².

Ca_Vγ7 (Transmembrane AMPA Receptor Regulatory Protein Isoform γ7) is highly expressed in Purkinje cells of the cerebellum and in glomerular synapses in the granule cell layer of the cerebellum and significantly enhances glutamate-evoked currents and modulates gating of AMPARs. Ca_Vγ7 appears to derive from cerebellar Golgi cells^2,3.                       

Ca_Vγ7 shows the largest sequence divergence compared to other TARP members. Its structure demonstrates a short C-terminus with an absence of the TTPV motif that is critical in the binding of TARP-associated AMPARs to PSD-95 and in clustering at the synapse³.

Several recent studies have suggested that Ca_Vγ7 has the ability to associate with extrasynaptic calcium-permeable AMPA receptors and plays an important role in regulating the presence of neuronal calcium-permeable AMPA receptors at synapses³. In addition, transfection of TARP Ca_Vγ7 causes AMPA receptors to resensitize upon continued glutamate application³.