The complete primary structure of GTP:AMP phosphotransferase from beef heart mitochondria.

To complete the amino acid sequence of GTP:AMP phosphotransferase (MgGTP + AMP in equilibrium with MgGDP + ADP) from beef heart mitochondria it was necessary to sequence an intermediate region of about 33 residues after position 102 [(1984) Eur. J. Biochem. 143, 331-339] and find a suitable overlap with the rest of the protein. The required peptides were obtained by cleaving the enzyme with endoproteinase Lys-C. One peptide, covering the region from residue 79 to 144, was sequenced up to residue 124. Another peptide, extending from residue 79 to 169, was subcleaved with Staphylococcus aureus V8 protease and provided the fragment from residue 99 to 139 which was sequenced. Several other peptides from endoproteinase Lys-C cleavage were used to check large sections of the previously published sequence work. The complete sequence contains 225 amino acids and has an Mr of 25 469.