title: Distinction of highly homologous pregnancy-specific glycoprotein (PSG) isoforms by differential absorption of antisera with recombinant PSG fusion protein domains.
abstract: The N-terminal domains of two different highly homologous isoforms of pregnancy-specific beta 1 glycoproteins (PSGs) were expressed in bacteria. The N-terminal domain of PSG1 (PSG1-N) and PSG3 (PSG3-N) were chosen since PSG3-N, but not PSG1-N, contains an RGD sequence. Immunosorbents were prepared using bacterially expressed fusion proteins with the respective N domains. Antibodies from a polyclonal antiserum against native PSG were eluted from PSG1-N and were subsequently absorbed against PSG3-N. Using this procedure, antibodies were generated that were able to bind to native PSG and PSG1-N, but not to PSG3-N. These results show that the antiserum against native PSG crossreacts with PSG isoforms of two subgroups. From the PSG antiserum, antibodies can be isolated that differentially bind to V-like PSG domains which differ by eight non-conservative amino acid substitutions, three of which are clustered in a position corresponding to the CDR III of immunoglobulin V region domains. Purification of antibody populations by this technique should make it possible to distinguish rapidly between highly homologous PSG isoforms in tissues and body fluids.
authors.affiliation: Abteilung für Klinische Chemie der Medizinischen Klinik, Universitätskrankenhaus Eppendorf, Hamburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Tschentscher
authors.forename: C
authors.initials: C
authors.lastname: Wagener
authors.forename: M
authors.initials: M
authors.lastname: Neumaier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D017931:DNA Primers / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
chemical_list: D017931:DNA Primers; D006023:Glycoproteins; D007106:Immune Sera; D011257:Pregnancy Proteins; D011993:Recombinant Fusion Proteins; D004247:DNA