The binding of Jun and Fos is based on interactions involving this molecule.
Most plant disease resistance genes code for proteins that have an nucleotide binding domain and contain elevated numbers of residues of this amino acid. Ribonuclease inhibitors are unusually rich in this non-Cysteine amino acid, which is an important part of a domain that has alternating alpha helices and beta strands that fold into horseshoe-shaped structures. High levels of this amino acid are found in most plant PAMP-receptor kinases and in human toll-like receptors. The binding of Jun and Fos is based on interactions involving this molecule. In a different protein motif, this amino acid is a prominent part of the hydrophobic channel formed due to the dimerization of two alpha helices. For 10 points, name this hydrophobic amino acid that is found at every seventh position in the "zipper" motif named for it. 
Most plant disease resistance genes code for proteins that have an nucleotide binding domain and contain elevated numbers of residues of this amino acid.
leucine [or L or Leu]