A severely truncated paralog of the AfuB uptake protein, homologous only to the last 20% of the intact protein in Actinobacillus. When overexpressed using vectors that provide a promoter and ribosome binding site (PubMed:15919996). Belongs to the binding-protein-dependent transport system permease family. FbpB subfamily. Could be the product of a pseudogene. The original protein is truncated by an IS1 element which is inserted right before residue 6. What was the original N-terminal of this protein is not known. Other genes of the operon were presumably also deleted by this IS1 event.