title: The functional units of a peptostreptococcal protein L.
abstract: Protein L is a cell-surface protein from Peptostreptococcus which interacts with immunoglobulin kappa light chains. A gene from Peptostreptococcus strain 3316 coding for protein L and fragments thereof were expressed in Escherichia coli. The peptides were examined for binding to immunoglobulin and serum albumin. The four C units were shown to be responsible for binding to immunoglobulin and the four D units for binding to albumin. This protein L molecule therefore binds to albumin at a site separate from that involved in binding to immunoglobulin. The albumin-binding units have high amino acid sequence identity with the albumin-binding units of streptococcal cell-surface proteins. The gene contains three sites available for internal initiation of translation resulting in three active proteins. The protein L molecule presented in this report was compared with a previously reported protein from Peptostreptococcus strain 312. The two proteins differ in several respects, including size and the number and types of repeat units.
authors.affiliation: Division of Biotechnology, PHLS Centre for Applied Microbiology and Research, Salisbury, Wiltshire, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Murphy
authors.forename: C J
authors.initials: CJ
authors.lastname: Duggleby
authors.forename: M A
authors.initials: MA
authors.lastname: Atkinson
authors.forename: A R
authors.initials: AR
authors.lastname: Trowern
authors.forename: T
authors.initials: T
authors.lastname: Atkinson
authors.forename: C R
authors.initials: CR
authors.lastname: Goward
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000378:metabolism; D008969:Molecular Sequence Data; D010462:Peptostreptococcus / Q000378:metabolism*; D011485:Protein Binding; D021382:Protein Sorting Signals / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C055047:Ig L-binding protein, Peptostreptococcus; D007147:Immunoglobulin Light Chains; D021382:Protein Sorting Signals; D012709:Serum Albumin