Differential Expression of the G Protein β5 Gene

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Abstract
: A neurally expressed heterotrimeric G protein β subunit, Gβ5, has been found to exhibit functional specialization with respect to its interactions with effector targets and Gα subunits. A splice variant of Gβ5 that contains an N‐terminal 42‐residue extension, Gβ5‐long, has been described in the retina. To define better the potential range of its specialized interactions, analysis of Gβ5 gene transcript and protein expression in mouse brain and other tissues and cell lines was performed. Quantification by ribonuclease protection assay of Gβ5 transcript expression in the developing brain demonstrates a fivefold increase that occurs postnatally. Analysis of transcript expression by in situ hybridization and ribonuclease protection assay indicates that the Gβ5 gene is differentially expressed among multiple adult mouse brain regions, including the motor and occipital cortex, the olfactory bulb and associated rhinencephalic structures, hypothalamus, pontine cochlear nuclei, and Purkinje cells in the cerebellum. Gβ5 is also expressed in several cultured cell lines of neuroendocrine origin, including murine αT3‐1 pituitary gonadotrophs and GT1‐7 hypothalamic cells, and rat PC12 pheochromocytoma cells. Immunoblotting of tissue homogenates with antibodies to two peptides common to Gβ5 and Gβ5‐long confirmed expression of Gβ5 in multiple brain regions and in spinal cord and expression of Gβ5‐long in retina. Taken together, these results suggest that the specialized molecular properties of Gβ5 have been adapted to diverse neural functions in the adult brain.