EXPRESSION OF GTP-BINDING PROTEIN ALPHA-SUBUNITS IN HUMAN THYMOCYTES

In this report, we investigate G protein alpha subunit diversity in hu man thymocytes, utilizing common properties shared by these genes and reverse transcription-polymerase chain reaction (RT-PCR). Sequence ana lysis of PCR amplified gene portions, indicate the presence of members from all four G-protein families that have been described thus far. T he alpha subunit genes identified are: G alpha(i1-3) and G alpha(z) bu t not G alpha(o) from the G(i) family, G alpha(s) from the G(s) family , G alpha(11), G alpha(q), and G alpha(16), from the G(q) family, and G alpha(12) and G alpha(13) from the G(12) family. Also in this report we present the nucleotide and predicted amino acid sequences of the h uman G alpha(13) cloned from a thymocyte cDNA library. The sequence of the human G alpha(13) has not been previously reported. Comparison of this sequence with the reported murine G alpha(13) shows >90% identit y at the deduced amino acid sequence level. We conclude that thymocyte s represent a useful experimental system for the study of G protein in volvement in immune responses and lymphocyte development.