Fig. 1

A schematic diagram of rec-eCGα/β mutants (a) and rec-eCGβ/α mutants (b). The wild-type protein and mutants with changed N- and O-linked oligosaccharide sites on eCG are shown. The Asn56 and 82 codons in the α-subunit were replaced by Gln or the CTP carrying O-linked oligosaccharides in the eCGβ-subunit was deleted by PCR mediated site-directed mutagenesis. The circle “N” denotes an N-linked oligosaccharide, “X” indicates the absence of an oligosaccharide, and “O-linked” represents an O-linked oligosaccharide. A total of 20 expression vectors (for 11 heterodimeric eCGs and nine tethered eCGs) were constructed (plasmids encoding heterodimeric eCGs were designated as pAB-eCGα/β, pAB-αΔ56/β, pAB-αΔ82/β, pAB-α/β Δ13, pAB-α/β-D, pAB-αΔ56,82/β, pAB-αΔ56/βΔ13, pAB-αΔ56/β-D, pAB-αΔ82/β-D, pAB-αΔ56.82/β-D, and pAB-αΔ56.82/βΔ13; plasmids encoding tethered eCGs were designated as pcDNA3-eCGβ/α, pcDNA3-β/αΔ56, pcDNA3-β-D/α, pcDNA3-β-D/αΔ56, pcDNA3-β-D/αΔ82, pcDNA3-β-D/αΔ56.82, pcDNA3-βΔ13-D/α, pcDNA3-βΔ13-D/αΔ56, and pcDNA3-βΔ13-D/αΔ56.82)