PROBLEM TO BE SOLVED: To provide polypeptide binding an Fc receptor (FcRn) of a newborn baby which is used as a medicine for modifying pharmacokinetic and pharmacodynamic properties as a therapeutic agent.SOLUTION: The invention relates to a class of engineered polypeptide having binding affinity to FcRn, and FcRn binding polypeptide, fusion protein and conjugate body include a sequence EX2X3X4AX6X7EIR WLPNLX16X17X18QR X21AFIX25X26 LX28X29.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】薬物動態学的および薬力学的特性を改変するための薬剤として、および治療薬として有用な新生児のFc受容体(FcRn)結合ポリペプチドの提供。【解決手段】FcRnへの結合親和性を有する操作されたポリペプチドのクラスに関し、配列EX2X3X4AX6X7EIR WLPNLX16X17X18QR X21AFIX25X26LX28X29を含むFcRn結合ポリペプチド、融合タンパク質およびコンジュゲート体。【選択図】なし