Regulates the trafficking and gating properties of AMPA-selective glutamate receptors (AMPARs). Promotes their targeting to the cell membrane and synapses and modulates their gating properties by slowing their rates of activation, deactivation and desensitization. Does not show subunit-specific AMPA receptor regulation and regulates all AMPAR subunits. Thought to stabilize the calcium channel in an inactivated (closed) state (By similarity). The L-type calcium channel is composed of five subunits: alpha-1, alpha-2/delta, beta and gamma. Interacts with the PDZ domains of DLG4/PSD-95 and DLG1/SAP97. May interact with GOPC. Acts as an auxiliary subunit for AMPA-selective glutamate receptors (AMPARs). Found in a complex with GRIA1, GRIA2, GRIA3, GRIA4, CNIH2, CNIH3, CACNG3, CACNG4, CACNG5, CACNG7 and CACNG8. Interacts with GRIA1 and GRIA2 (By similarity). Interacts with MPP2. Brain. Phosphorylation of Thr-321 by PKA impairs interaction with DLG1 and DLG4. Defects in Cacng2 cause the stargazer (stg) phenotype. Stg mice have spike-wave seizures characteristic of absence epilepsy, with accompanying defects in the cerebellum and inner ear. Belongs to the PMP-22/EMP/MP20 family. CACNG subfamily.