GTP-specific succinyl-CoA synthetase functions in the citric acid cycle (TCA), coupling the hydrolysis of succinyl-CoA to the synthesis of GTP and thus represents the only step of substrate-level phosphorylation in the TCA. The beta subunit provides nucleotide specificity of the enzyme and binds the substrate succinate, while the binding sites for coenzyme A and phosphate are found in the alpha subunit. CoA + GTP + succinate = GDP + phosphate + succinyl-CoA Binds 1 Mg(2+) ion per subunit. Carbohydrate metabolism; tricarboxylic acid cycle; succinate from succinyl-CoA (ligase route): step 1/1. Heterodimer of an alpha and a beta subunit. The beta subunit determines specificity for GTP. Mainly expressed in liver, kidney, heart, spleen and skeletal muscle. Also found in intestine and colon, and in low amounts in lung, brain, prostate, testis and ovary. Belongs to the succinate/malate CoA ligase beta subunit family. GTP-specific subunit beta subfamily. Extended N-terminus. Truncated C-terminus.