Acetohydroxy acid synthase (also known as acetolactate
synthase) is a key enzyme that catalyzes the first common
step in the biosynthesis of the essential branched-chain amino
acids isoleucine, leucine, and valine
The gm-hra gene has been modified by site directed
mutagenesis (P183A and W560L) from the native soybean als
gene and encodes a version of the enzyme that is tolerant to
als inhibitors such as sulfonylurea herbicide.
It also contains 15 additional nucleotides from the native
als gene 5'UTR.