While plants mainly rely on the use of inorganic nitrogen sources like ammonium and nitrate, soil-borne microorganisms like the ectomycorrhizal fungus Hebeloma cylindrosporum can also take up soil organic N in the form of amino acids and peptides that they use as nitrogen and carbon sources. Following the previous identification and functional expression in yeast of two PTR-like peptide transporters, the present study details the functions and substrates of HcPTR2A and HcPTR2B by analysing their transport kinetics in Xenopus laevis oocytes. While both transporters mediated high-affinity di- and tripeptide transport, HcPTR2A also showed low-affinity transport of several amino acids—mostly hydrophobic ones with large side chains.

植物主要依靠铵和硝酸盐等无机氮源的利用，而土壤外生微生物如菌根菌（Heleboma cylindrosporum）也可以以氨基酸和肽的形式吸收土壤有机氮，用作氮和碳源。继先前在酵母中鉴定出两个PTR样肽转运蛋白并在酵母中进行功能性表达后，本研究通过分析非洲爪蟾卵母细胞中的转运动力学，详细介绍了HcPTR2A和HcPTR2B的功能和底物。尽管这两种转运蛋白均介导了高亲和力的二肽和三肽转运，但HcPTR2A还显示出几种氨基酸的低亲和力转运-大多数是带有大侧链的疏水氨基酸。