PapG, the adhesin of the P-pili, is situated at the tip and is only a minor component of the whole pilus structure. A two-domain structure has been postulated for PapG; a carbohydrate binding N-terminus (this domain) and chaperone binding C-terminus. The carbohydrate-binding domain interacts with the receptor glycan [1,2].

1: The solution structure of PapGII from uropathogenic Escherichia coli and its recognition of glycolipid receptors. Sung MA, Fleming K, Chen HA, Matthews S; EMBO Rep 2001;2:621-627. PMID:11454740

2: Structural basis of the interaction of the pyelonephritic E. coli adhesin to its human kidney receptor. Dodson KW, Pinkner JS, Rose T, Magnusson G, Hultgren SJ, Waksman G; Cell 2001;105:733-743. PMID:11440716