Part of the ABC transporter complex GltIJKL involved in glutamate and aspartate uptake. Probably responsible for energy coupling to the transport system. a polar amino acid(out) + ATP + H2O = a polar amino acid(in) + ADP + H(+) + phosphate ATP + H2O + L-glutamate(out) = ADP + H(+) + L-glutamate(in) + phosphate ATP + H2O + L-aspartate(out) = ADP + H(+) + L-aspartate(in) + phosphate The complex is composed of two ATP-binding proteins (GltL), two transmembrane proteins (GltJ and GltK) and a solute-binding protein (GltI). Belongs to the ABC transporter superfamily.