Definition of IgG- and albumin-binding regions of streptococcal protein G

Research output: Contribution to journalArticle

Abstract

Protein G, the immunoglobin G-binding surface protein of group C and G streptococci, also binds serum albumin. The albumin-binding site on protein G is distinct from the immunoglobulin G-binding site. By mild acid hydrolysis of the papain-liberated protein G fragment (35 kDa), a 28-kDa fragment was produced which retained full immunoglobulin G-binding activity (determined by Scatchard plotting) but had lost all albumin-binding capacity. A protein G (65 kDa), isolated after cloning and expression of the protein G gene in Escherichia coli, had comparable affinity to immunoglobulin G (5-10 X 10(10)M-1), but much higher affinity to albumin than the 35- and 28-kDa protein G fragments (31, 2.6, and 0 X 10(9)M-1, respectively). The amino-terminal amino acid sequences of the 65-, 35-, and 28-kDa fragments allowed us to exactly locate the three fragments in an overall sequence map of protein G, based on the partial gene sequences published by Guss et al. (Guss, B., Eliasson, M., Olsson, A., Uhlen, M., Frej, A.-K., Jörnvall, H., Flock, J.-I., and Lindberg, M. (1986) EMBO J. 5, 1567-1575) and Fahnestock et al. (Fahnestock, S. R., Alexander, P., Nagle, J., and Filpula, D. (1986) J. Bacteriol. 167, 870-880). In this map could then be deduced the location of three homologous albumin-binding regions and three homologous immunoglobulin G-binding regions.

Details

Authors
Organisations
External organisations
  • Hagedorn Research Institute, Copenhagen University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medicinal Chemistry
  • Infectious Medicine

Keywords

  • Amino Acid Sequence, Antigens, Bacterial, Bacterial Proteins/immunology, Binding Sites, Chromatography, Affinity, Electrophoresis, Polyacrylamide Gel, Humans, Immunoglobulin G/metabolism, Kinetics, Molecular Weight, Serum Albumin/metabolism
Original languageEnglish
Pages (from-to)13388-91
JournalJournal of Biological Chemistry
Volume262
Issue number28
Publication statusPublished - 1987 Oct 5
Publication categoryResearch
Peer-reviewedYes