title: Design, expression and characterization of a soluble single-chain functional human neonatal Fc receptor.
abstract: The neonatal Fc receptor (FcRn) is responsible for transporting maternal IgGs to fetus/newborns and maintaining the homeostasis of IgGs in adults. FcRn resembles class I major histocompatibility complex in structure, and is composed of a transmembrane heavy chain and an invariant beta 2 microglobulin. Changes in the affinity of IgGs to FcRn lead to changes in the half-life of engineered IgGs and Fc fusion proteins. Longer half-life of therapeutic antibodies means lower dose and longer interval between administering. For some diagnostic agents including imaging or radio-labeled agents a shorter half life in circulation results in lower non-specific binding and decreased side effects. Therefore, studying the interaction of FcRn and therapeutic antibodies has direct clinical implications. A reliable method to prepare soluble and functional FcRn protein is essential for such studies. In this study, we describe a new method to express in mammalian cells soluble human FcRn (sFcRn) as a single-chain soluble fusion protein. The highly hydrophilic beta 2 microglobulin was joined with the hydrophobic heavy chain via a 15 amino acid linker. The single-chain fusion protein format not only improved the expression level of the heavy chain but also simplified the purification process. The sFcRn maintained its pH-dependent binding to IgG. This method typically yielded ∼1 mg/100ml culture without optimization, and is easy to scale up for production of large quantities.
authors: Protein Interactions Group, CCR Nanobiology Program, NCI-Frederick, NIH, Frederick, MD 21702, United States. fengya@mail.nih.gov
authors: Yang
authors: Y
authors: Feng
authors: Rui
authors: R
authors: Gong
authors: Dimiter S
authors: DS
authors: Dimitrov
mesh_terms: D000595:Amino Acid Sequence; D001666:Binding Sites, Antibody; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods*; D015395:Histocompatibility Antigens Class I / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008969:Molecular Sequence Data; D011961:Receptors, Fc / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D012995:Solubility; D001613:beta 2-Microglobulin / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; D001613:beta 2-Microglobulin; C100688:Fc receptor, neonatal