Colony queen number, a major feature of social organization, is associated with worker genotype for Gp-9. Colonies are headed by either a single reproductive queen (monogyne form) or multiple queens (polygyne form). Differences in worker Gp-9 genotypes between social forms may cause differences in workers' abilities to recognize queens and regulate their numbers (By similarity). Homodimer. Alleles B2 and B3 are shown, monogyne population from Brazil. Belongs to the PBP/GOBP family.