GABARAP is not essential for GABA receptor targeting to the synapse

GABA(A) receptors (GABA(A)Rs) containing the gamma2 subunit are thought to require the interacting protein GABARAP (GABA(A)R associated protein) for trafficking to the neuronal plasma membrane. In order to assess whether GABARAP is required for GABA(A) receptor accumulation at synaptic sites, we analysed a GABARAP knockout mouse. GABARAP deficient mice are phenotypically normal and do not show up-regulation of other GABARAP homologues. Also, the total number of GABA(A)Rs, as assessed by benzodiazepine binding, is unaffected by the loss of GABARAP. Immunocytochemistry of cortical sections showed no differences in the expression and punctate distribution of the gamma2 subunit and the receptor anchoring protein gephyrin between GABARAP deficient and wild-type mice. Thus, GABARAP is not essential for trafficking gamma2 subunit containing GABA(A)Rs to the neuronal plasma membrane or targeting them to inhibitory synapses.