We cloned a cDNA molecule complementary to human brain caudate mRNA which codes for theα subunit of the G protein (Gsα) that stimulates adenylyl cyclase. A λZAP II cDNA library derived from human caudate was screened with a [α-32 P] - labeled
probe
for recombinant DNA that codes for Gsα. The probe was an EcoRI digested 3' fragment of Gsα cDNA from rat olfactory neuroepithelium. The cDNA encoding Gsα from human brain caudate (human CGsα) contained 1,392 residues, similar to the length
reported
for rabbit liver and human basal ganglia but different from that of rat brain (which lacks 59 amino acid residues at the 5' end). An open reading frame 1,026 nucleotides long was found to encode 341 amino acid residues with a calculated molecular
weight
of 39,500. The nucleotide sequence of human CGSα cDNA was homologous to those from rabbit (99.6%), rat (90.4%) and human(89.2%) basal ganglia. However, human CGsα cDNA differed from the other Gsα cDNAs due to the presence of a deletion of an
adenylate residue between nucleotides 1,114 and 1,115. With respect to the amino acid sequence deduced from the cloned cDNA, human cGsα cDNA had over 96% homology with those from rabbit, rat and huan basal ganglia. The G region (which interacts
directly with the guanine ring of GTP in all GTP-binding proteins) and the G' region (which has GTPase activity) were completely conserved in the human CGs cDNA we studied..
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