Molecular Cloning and Characterization of GPA1, a G Protein {alpha} Subunit Gene from Arabidopsis thaliana

Abstract

We have isolated a gene coding for a G protein {alpha} subunit from the flowering plant Arabidopsis thaliana. This gene, named GPA1, was isolated by using a DNA probe generated by polymerase chain reaction based on protein sequences from mammalian and yeast G protein {alpha} subunits. The sequences of genomic and cDNA clones indicate that GPA1 has 14 exons, and the deduced amino acid sequence shows that the GPA1 gene product (GP{alpha}1) has 383 amino acid residues (44,582 Da). The GP{alpha}1 protein exhibits similarity to all known G protein {alpha} subunits--36% of its amino acids are identical and 73% are similar (identical and conservative changes) to mammalian inhibitory guanine nucleotide-binding regulatory factor {alpha} subunits and transducins. Furthermore, the GP{alpha}1 protein has all of the consensus regions for a GTP-binding protein. The GPA1-encoded mRNA of 1.55 kilobases is most abundant in vegetative plant tissues, as determined by RNA blot analysis. Restriction fragment length polymorphism mapping experiments show that GPA1 is {approx} 1.2 centimorgans from the visible marker er on chromosome 2.

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