Essential for nitrogen assimilation, distribution and remobilization within the plant via the phloem. ATP + H2O + L-aspartate + L-glutamine = AMP + diphosphate + H(+) + L-asparagine + L-glutamate Amino-acid biosynthesis; L-asparagine biosynthesis; L-asparagine from L-aspartate (L-Gln route): step 1/1. A number of isoforms are produced. According to EST sequences. By dark. Down-regulated by light and sucrose. Plants over-expressing ASN1 have increased content of free amino acids (mainly Asn) in flowers, siliques and seeds.