9.B.67 The O-antigen Polymerase (OAP) Family
The O-antigen polymerase (ligase) family (COG3307) consists of proteins of this function. It is probable that O-antigen polymerases facilitate export of intermediates of LPS biosynthesis. Several of the proteins listed in this table are distantly related to each other, but homology has been established (DE Chen and MH Saier, unpublished results). This family may be distantly related to 9.B.128, also designated as an O-antigen polymerase family. A homologue designated IctB or ORF467 in Synechococcus sp. strain PCC7942 was reprted to be a Na+:HCO3- symporter, but this conclusion may have been in error.
The probable transport reaction proposed for OAP family members is:
O-antigen precursor (in) → O-antigen precursor (out).