Binds (in a non-immune fashion) to the Fc portion of human IgA and IgG; binding occurs on the cell surface. Confers the ability to survive exposure to human serum exposure (PubMed:10722621). Binds to the Fc portion of human IgG, IgA and to whole mouse antibodies also via Fc (PubMed:19303642). Upon overexpression cells acquire an extra cell surface layer that forms a zipper-like contact between cells; cells autoagglutinate and form biofilm more readily, suggesting it may play a role in defense against a host (PubMed:21742268). Homotrimer; can probably form mixed heterotrimers in vivo (Probable). Will form mixed heterotrimers with EibA or EibC; these are correctly located in the outer membrane and bind IgG Fc, although less well than homotrimers (PubMed:22155776). In denaturing gels runs as a band of about 210 kDa (PubMed:10722621). Binds the Fc portion of immunoglobulins; binds more than 1 Fc per subunit, can be modeled to bind 3 Fc per trimer (PubMed:19303642) (Probable). The C-terminal translocator domain is localized in the outer membrane and the passenger domain is at the cell surface. In strain ECOR 9 expression is greater at 37 than 27 degrees Celsius and increases upon entry into stationary phase (at protein level). Upon expression from a plasmid in strain AB1157 (with its own leader sequence) more protein is seen at 37 than 27 degrees Celsius (at protein level). The signal peptide, cleaved at the inner membrane, guides the autotransporter protein to the periplasmic space (By similarity). Then, trimerization and insertion of the C-terminal translocator domain in the outer membrane forms a hydrophilic pore for the translocation of the passenger domain to the bacterial cell surface (PubMed:22155776). The crystallized passenger domain (residues 161-440) is an entwined, elongated trimer with a head domain, a neck and 2 extended coiled-coil regions of differing handedness separated by a saddle region. There are a number of cavities in the first (right-handed, RHcc) coiled-coil domain that may allow bending of the extended structure. Smaller cavities in the second (left-handed, LHcc) coiled-coil bind 5 Cl(-) and one water molecule. The Fc portion of IgG has been modeled to bind to the LHcc domain just under the saddle; up to 3 Fc can bind to the trimer (PubMed:21742268). Encoded in a prophage region of strain ECOR 9, upon UV treatment bacteriophage containing this gene can be isolated. Belongs to the autotransporter-2 (AT-2) (TC 1.B.40) family. Eib subfamily.