Catalyzes the reversible transfer of the terminal phosphate group between ATP and AMP. Also displays broad nucleoside diphosphate kinase activity. Plays an important role in cellular energy homeostasis and in adenine nucleotide metabolism (By similarity) (PubMed:21080915, PubMed:23416111, PubMed:2542324). Also catalyzes at a very low rate the synthesis of thiamine triphosphate (ThTP) from thiamine diphosphate (ThDP) and ADP (By similarity). {ECO:0000250|UniProtKB:P05081, ECO:0000255|HAMAP-Rule:MF_03171, ECO:0000269|PubMed:21080915, ECO:0000269|PubMed:23416111, ECO:0000269|PubMed:2542324}. This is the function of ENSG00000106992 (AK1, adenylate kinase 1).