1.B.16 The Short Chain Amide and Urea Porin (SAP) Family
The SAP family includes an outer membrane porin (FmdC) found in the bacterium Methylophilus methylotrophus. Its synthesis is inducible by short chain amides and urea, and the protein presumably transports these molecules across the outer membrane when these nitrogen sources are present at low concentrations. The protein is 390 amino acyl residues in length and consists largely of β-structure. It has only one homologue (25% identity), a protein found in Aquifex aeolicus (385 aas).
The generalized transport reaction catalyzed by FmdC is:
Amides (out) Amides (periplasm)