Part of the accessory SecA2/SecY2 system specifically required to export GspB, a serine-rich repeat cell wall protein encoded upstream in the same operon. Part of the accessory SecA2/SecY2 protein translocation apparatus required to export cell wall protein GspB. Loss of export of cell wall protein GspB, the protein accumulates intracellularly in protoplasts. Belongs to the accessory Sec system protein Asp1 family.