Fig. 1 Structure of human RGS6 proteins encoded by 36 RGS6 cDNAs. The 36 different RGS6 cDNAs encode RGS6 proteins with long (L) or short (S) N-terminal domains, 7 distinct C-terminal domains and complete or incomplete GGL domains. RGS6 proteins with the long and short N-terminal domain are named RGS6L and RGS6S, respectively. The identity of the type of C-terminal domain is indicated by alpha, beta, gamma, delta, epsilon, eta, and zeta designations with alpha and beta forms existing in two forms, with (alpha1 and beta1) and without (alpha2 and beta2) an 18 amino acid sequence (encoded by exon 18 of the RGS6 gene). Finally, the absence of a complete GGL domain is indicated by (-GGL).