A complex of three secretory proteins that carry out secretion in the type I secretion system: an inner membrane transport ATPase (termed ABC protein for ATP-binding cassette), which provides the energy for protein secretion; an outer membrane protein, which is exported via the sec pathway; and a membrane fusion protein, which is anchored in the inner membrane and spans the periplasmic space. [ http://www.ncbi.nlm.nih.gov/pubmed/9618447 ]