The Vfaap1 gene from Vicia faba encodes an amino acid permease.
Amino acid permeases transport amino acids from the plant vascular
tissue into the symplasts of plant cells. They are differentially
expressed according to plant development and tissue, and exhibit a
range of specificity patterns for amino acids. VfAAP1 mediates the
transport of a range of amino acids (mainly cysteine, arginine,
glutamine, serine, leucine, methionine, histidine, glycine and
threonine) with particular emphasis on cysteine. The formation of
the amino acid permease of the field bean in pea seeds and the
results in an increase in the seed protein content.