Nucleotide and amino acid sequence ofXenopus NT-3. The deduced amino acid sequence, insingle-letter code, is shown below the nucleotide sequence. Primers used for cloning areunderlined (in the order of appearance: HNT 3, XNT 5, XNT 4, and HNT 6). Primers used for the quantitative RT-PCR assay areboxed (NT-3-1 and NT-3-2).