A, Comparison of amino acid sequences of thioredoxins. The asterisks denote the conserved redox active site, and dashes represent gaps introduced to optimize alignment. GenBank accession numbers of the thioredoxins are as follows (in parentheses): Arabidopsis (AraTrx 3, CAA84611), tobacco (tobacco h1, PIR-S16590), human (TRX, PIR-JH0568), and yeast (TRX1p, NP_013144). B, Comparison of amino acid sequences of β-carotene hydroxylases. The asterisks identify conserved motif 1. GenBank accession numbers of the β-carotene hydroxylases are as follows (in parentheses): citrus (AAG33636), Arabidopsis (NP_194300), and rice (CAE03252). The nucleotide sequences have been submitted to GenBank with accession numbers AY575954 (thioredoxin) and AY575953 (β-carotene hydroxylase).