Enables several functions, including magnesium ion binding activity; purine ribonucleotide binding activity; and ribose phosphate diphosphokinase activity. Involved in 5-phosphoribose 1-diphosphate biosynthetic process; AMP biosynthetic process; and animal organ regeneration. Part of ribose phosphate diphosphokinase complex. Orthologous to human PRPS2 (phosphoribosyl pyrophosphate synthetase 2). [provided by Alliance of Genome Resources, Apr 2022]