phosphoribosylpyrophosphate

noun

phos·​pho·​ri·​bo·​syl·​py·​ro·​phos·​phate ˌfäs-phō-ˌrī-bə-ˌsil-ˌpī-rō-ˈfäs-ˌfāt 

: a substance that is formed enzymatically from ATP and the phosphate of ribose and that plays a fundamental role in nucleotide synthesis