Distribution of C-terminal splice variant of G alpha i2 in rat and monkey brain.

The significance of Galphai2 in neural signal transmission is well defined. However, the function of its alternative splice variant named sGi2 is unknown. Therefore here, we have studied the localization of sGi2 protein in rat and monkey brain at light and electron microscopy level. We found that this novel protein is widely expressed in rat and monkey brain regions, which are known to play crucial role in brain functions. Hippocampus, cerebral cortex, amygdala, thalamus, striatum, nucleus accumbens, olfactory tubercle and dopaminergic cell groups of substantia nigra, hypothalamus and olfactory bulb showed strong labeling with anti-sGi2. At subcellular level, sGi2 protein was localized in intracellular compartments, including endoplasmic reticulum, Golgi complex, mitochondria and nucleus. This protein was also found localized extra-synaptically in both axons and spines, which were making excitatory as well as inhibitory synaptic contacts. Moreover, the frequent localization of sGi2 protein in neck of spines further suggests that this protein may not engage directly in neuronal signal transmission but could influence other participating proteins of this process.