title: Origin of guanine nucleotides in isolated heart mitochondria.
abstract: Presence of guanine nucleotide within the matrix of mitochondria is uncontested; the mechanism by which GTP takes up residence in the matrix is unknown. In this report, we demonstrate for the first time that direct transport of guanine nucleotide across the inner membrane of heart mitochondria is possible. Transport of guanine nucleotides from the medium to the matrix was suggested by inhibition of translation in isolated rat heart mitochondria when GTP-gamma-S was added to the medium. This result suggested that GTP was one source of matrix GTP. Other sources were investigated by measuring matrix uptake and conversion to GTP of several purines, purine nucleosides, and purine nucleotides. Results demonstrated that [14C]-guanine and [3H]-guanosine were not taken up by isolated mitochondria and were not converted to any other compound. While [14C]-ATP and [3H]-AMP were taken up readily into the matrix, radioactivity was never associated with a guanine compound. [3H]-IMP was not taken up into the matrix and was never converted to another compound. Our data showed that label added as [3H]-GTP, [3H]-GDP, or [3H]-GMP was readily taken up and concentrated in the matrix of isolated mitochondria.
authors: South Bend Center for Medical Education, Indiana University School of Medicine, 46556, USA.
authors: E E
authors: EE
authors: McKee
authors: A T
authors: AT
authors: Bentley
authors: R M
authors: RM
authors: Smith
authors: C E
authors: CE
authors: Ciaccio
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D006147:Guanine / Q000378:metabolism / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000378:metabolism*; D006151:Guanosine / Q000378:metabolism / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006157:Guanosine Monophosphate / Q000378:metabolism / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D007291:Inosine Monophosphate / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013873:Thionucleotides / Q000494:pharmacology; D013997:Time Factors
chemical_list: D006150:Guanine Nucleotides; D013873:Thionucleotides; D006151:Guanosine; D007291:Inosine Monophosphate; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000249:Adenosine Monophosphate; D006147:Guanine; D000244:Adenosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D006157:Guanosine Monophosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate