High-yield Expression and Characterization of Syndecan-4 Extracellular, Transmembrane and Cytoplasmic Domains

Abstract

E-mail: yakim@hufs.ac.krReceived December 27, 2012, Accepted January 21, 2013The syndecan family consists of four transmembrane heparan sulfate proteoglycans present in most cell typesand each syndecan shares a common structure containing a heparan sulfate modified extracellular domain, asingle transmembrane domain and a C-terminal cytoplasmic domain. To get a better understanding of themechanism and function of syndecan-4 which is one of the syndecan family, it is crucial to investigate its three-dimensional structure. Unfortunately, it is difficult to prepare the peptide because it is membrane-bound proteinthat transverses the lipid bilayer of the cell membrane. Here, we optimize the expression, purification, andcharacterization of transmembrane, cytoplasmic and short extracellular domains of syndecan4 (syndecan-4eTC). Syndecan-4 eTC was successfully obtained with high purity and yield from the M9 medium. Thestructural information of syndecan-4 eTC was investigated by MALDI-TOF mass (MS) spectrometry, circulardichroism (CD) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. It was confirmed thatsyndecan-4 eTC had an α-helical multimeric structure like transmembrane domain of syndecan-4 (syndecan-4 TM) in membrane environments. Key Words : Syndecan, Syndecan-4, Transmembrane, NMR spectroscopy, Membrane proteinIntroductionThe syndecan family consists of heparan sulfate proteo-glycans, which are present on the surface of all cell types inhumans. This family regulates cell-to-cell interaction, celladhesion, cell proliferation and angiogenesis, as well ashelps in healing wounds by activation of growth factors.