Besides a role in phosphate supply, ectomycorrhizas play a crucial role in nitrogen nutrition of plants. The ectomycorrhizal association between Hebeloma cylindrosporum and Pinus pinaster serves as a model system accessible to molecular manipulation. Hebeloma mycelium is able to take up and use amino acids as the sole nitrogen source. Suppression cloning allowed identification of a Hebeloma transporter (HcGAP1) mediating histidine uptake. HcGAP1 mediates secondary active uptake of a wide spectrum of different amino acids. The secondary active transport mechanism together with the expression in hyphae, but not in mycorrhizas, indicate a role in uptake of organic nitrogen from the soil.