A candidate target for G protein action in brain

An effector candidate for G protein action, GRIN1, was identified by screen ing a cDNA expression library with phosphorylatled GTP gamma S-G(z)alpha as a probe. GRIN1 is a novel protein without substantial homology to known pr otein domains. It is expressed largely in brain and binds specifically to a ctivated G(z)alpha, G(o)alpha, and G(i)alpha through its carboxyl-terminal region. The protein KIAA0514 (GRIN2) is homologous to GRIN1 at its carboxyl terminus and also binds to activated G(o)alpha. Both GRIN1 and G(o)alpha a re membrane-bound proteins that are enriched in the growth cones of neurite s. Coexpression of GRIN1, or GRIN2 with activated G(o)alpha causes formatio n of a network of fine processes in Neuro2a cells, suggesting that these pa thways may function downstream of G(o)alpha to control growth of neurites.