Involved in the response to the germinative mixture of L-asparagine, glucose, fructose and potassium ions (AGFK). Could be an amino acid transporter. Cannot stimulate germination in the absence of gerD and gerK gene products (fructose and glucose receptors, respectively). Expressed in the forespore compartment of the developing sporangium. Belongs to the amino acid-polyamine-organocation (APC) superfamily. Spore germination protein (SGP) (TC 2.A.3.9) family.