Members of this family occur in Gram-positive bacteria as part of a type IV pilus system used for DNA binding and uptake when species such as Streptococcus pneumoniae or Bacilus subtilis are in a competent state for natural transformation. Members of this family, typically called ComGB (second protein of the ComG operon), belong more broadly to the family of GspF, part of type 2 secretion systems (T2SS) in Gram-negative bacteria.
Jiyao W et al.(2023). "The conserved domain database in 2023.",