From 2011.igem.org

RsaA

RsaA is the surface-layer (S-layer) protein produced by the gram-negative bacteria Caulobacter crescentus. It covers the surface of the cell in a 2-D hexameric crystal and accounts for 10-12% of total protein synthesis by the cell.¹ Key regions of the protein include the N-terminal region, which is necessary for binding of the protein to the surface of the cell, and the C-terminal region, which acts as a secretion tag.²