Isolation and characterization of a complementary DNA for the nuclear-coded precursor of the beta-subunit of bovine mitochondrial F1-ATPase.

We have isolated a cDNA clone encoding the precursor of the beta-subunit of the bovine heart mitochondrial F1-ATPase. Two probes were used to isolate this precursor from a bovine heart cDNA library. One probe was a mixed-sequence oligonucleotide directed against a portion of the amino acid sequence of the mature protein, and the other probe was the F1-ATPase beta-subunit gene from Saccharomyces cerevisiae. Determination of the nucleotide sequence of this cDNA reveals that it contains a 1584-nucleotide-long open reading frame that encodes the complete mature beta-subunit protein and a 48 amino acid long NH2-terminal extension. This amino-terminal presequence contains four basic arginine residues, one acidic glutamic acid residue, four polar uncharged serine residues, and five proline residues. Southern blot hybridization analyses suggest that the bovine F1-ATPase beta-subunit precursor is encoded by a single genetic locus. RNA blot hybridization analyses reveal a single mRNA species of approximately 1.9 kilobases from both bovine liver and heart.