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The adenine nucleotide translocator of higher plants is synthesized as a large precursor that is processed upon import into mitochondria.
Author(s) -
Winning BM,
Sarah CJ,
Purdue PE,
Day CD,
Leaver CJ
Publication year - 1992
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1992.t01-15-00999.x
Subject(s) - adenine nucleotide translocator , translocator protein , biology , mitochondrion , biochemistry , amino acid , complementary dna , nucleic acid sequence , ant , peptide sequence , nucleotide , gene , ecology , immunology , neuroinflammation , inflammation
Summary Two maize genes and cDNAs encoding the mitochondrial adenine nucleotide translocator (ANT), a nuclear‐encoded inner mitochondrial membrane carrier protein, have previously been isolated in this laboratory. Sequence analysis revealed the existence of much longer open reading frames than the corresponding fungal and mammalian ANT genes. Potato ANT cDNAs have subsequently been isolated and sequenced and alignment of the deduced plant amino acid sequences with the equivalent fungal and mammalian polypeptides indicated that the plant proteins contain N‐ terminal extensions. When the plant cDNA clones are expressed in vitro they direct the synthesis of precursor proteins that are specifically processed at the N‐terminus upon import into isolated mitochondria. N‐ terminal amino acid sequence data obtained from the native proteins purified from both maize and potato mitochondria has allowed identification of the putative processing sites. Further import analysis has shown that two distinct regions of the maize precursor protein contain targeting information, the 97 amino acids at the N‐ terminus and the 267 C‐terminal amino acids. This is the first report that provides experimental evidence that the adenine nucleotide translocator of higher plants is synthesized as a large precursor protein that is specifically cleaved upon import into mitochondria. Import of ANT into higher plant mitochondria therefore appears to be different to the corresponding process in fungal and mammalian systems where targeting of ANT to mitochondria is mediated by internal signals and there is no N‐terminal processing.