Human cDNA clones for four species of G(α(s)) signal transduction protein

λgt11 cDNA libraries derived from human brain were screened with oligonucleotide probes for recombinants that code for α subunits of G signal transduction proteins. Eleven α(s) clones were detected with both probes and characterized. Four types of α(s) cDNA were cloned that differ in nucleotide sequence in the region that corresponds to amino acid residues 71-88. The clones differ in the codon for α(s) amino acid residue 71 (glutamic acid or aspartic acid), the presence or absence of codons for the next 15 amino acid residues, and the presence or absence of an adjacent serine residue. S1 nuclease protection experiments revealed at least two forms of α(s) mRNA. A mechanism for generating four species of α(s) mRNA by alternative splicing of precursor RNA is proposed.