This is a family of a major outer membrane lipoprotein, OprL that is an alanine-zipper. Zipper motifs are a seven-repeat motif where the first and fourth positions are occupied by an aliphatic residue, usually a leucine. These residues are positioned on the outside of the coil such as to bind firmly to one or more monomers of the protein to create a triple or five-helical coiled-coil that probably forms a seam in a membrane.