Polarity-determining protein which forms a conjugate with the ubiquitin-like modifier HUB1. Involved in bud site selection and cellular morphogenesis during conjugation. Required for pseudohyphal growth. Conjugated with HUB1. HUB1 has not the classical C-terminal Gly residue, so it is still unknown how conjugation may occur. Sites of polarized growth as bud tip, bud neck and mating projection. Hub1 is necessary for the proper location to mating projections after pheromone alpha treatment. Present with 672 molecules/cell in log phase SD medium. Truncated C-terminus.