Colony Filtration Blots for identification of soluble protein expression in E. coli. E. coli colonies expressing domains ATS, CIDR1α and DBL1α were induced and lysed on a membrane filter. Soluble protein from each cell within the colony diffuses through the filter and is captured on a nitrocellulose membrane placed under the membrane filter . Detection with antibody reagents directed against the fusion tag, shows spots indicating the presence of soluble protein. Intensity of the spot corresponds to the yield of soluble protein. The arrow shows the increasing expression of soluble protein for the PfEMP1 domain types compared.