Cobalt uptake substrate-specific transmembrane region
This family of proteins forms part of the cobalt-transport complex in prokaryotes, CbiMNQO. CbiMNQO and NikMNQO are the most widespread groups of microbial transporters for cobalt and nickel ions and are unusual uptake systems as they consist of eg two transmembrane components (CbiM and CbiQ), a small membrane-bound component (CbiN) and an ATP-binding protein (CbiO) but no extracytoplasmic solute-binding protein. Similar components constitute the nickel transporters with some variability in the small membrane-bound component, either NikN or NikL, which are not similar to CbiN at the sequence level. CbiM is the substrate-specific component of the complex and is a seven-transmembrane protein. The CbiMNQO and NikMNQO systems form part of the coenzyme B12 biosynthesis pathway. The NikM protein is pfam10670.