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.
In the donor organism, Vicia faba, the Vfaa1 gene is expressed
predominantly in the storage parenchyma cells of the cotyledons in
developing seeds, particularly in early development. The strongest
expression of Vfaap1 precedes the beginning of the expression of
storage protein genes. 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.