Generic peptide substrate for use in TR-FRET biochemical kinase assays. Refer to Selector Guide for validated kinases. ULight™-labeled synthetic peptide derived from amino acids 1015-1027 of human Janus kinase 1 (JAK-1). The ULight-JAK-1 peptide can be phosphorylated at Tyr1023 by JAK3 and several other tyrosine kinases. Peptide sequence: CAGAGAIETDKEYYTVKD