title: Human salivary agglutinin binds to lung surfactant protein-D and is identical with scavenger receptor protein gp-340.
abstract: Salivary agglutinin is a 300-400 kDa salivary glycoprotein that binds to antigen B polypeptides of oral streptococci, thereby playing a role in their colonization and the development of caries. A mass spectrum was recorded of a trypsin digest of agglutinin. A dominant peak of 1460 Da was sequenced by quadrupole time-of-flight (Q-TOF) tandem MS. The sequence showed 100% identity with part of the scavenger receptor cysteine-rich ('SRCR') domain found in gp-340/DMBT1 (deleted in malignant brain tumours-1). The mass spectrum revealed 11 peaks with an identical mass as a computer-simulated trypsin digest of gp-340. gp-340 is a 340 kDa glycoprotein isolated from bronchoalveolar lavage fluid that binds specifically to lung surfactant protein-D. DMBT1 is a candidate tumour suppressor gene. A search in the human genome revealed only one copy of this gene. The molecular mass, as judged from SDS/PAGE and the amino acid composition of agglutinin, was found to be nearly identical with that of gp-340. It was shown by Western blotting that monoclonal antibodies against gp-340 reacted with salivary agglutinin, and monoclonals against agglutinin reacted with gp-340. It was demonstrated that gp-340 and agglutinin bound in a similar way to Streptococcus mutans and surfactant protein-D. Histochemically, the distribution of gp-340 in the submandibular salivary glands was identical with the agglutinin distribution, as shown in a previous paper [Takano, Bogert, Malamud, Lally and Hand (1991) Anat. Rec. 230, 307-318]. We conclude that agglutinin is identical with gp-340, and that this molecule interacts with S. mutans and surfactant protein-D.
authors.affiliation: Department of Basic Dental Sciences, Academic Centre for Dentistry Amsterdam (ACTA), van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands. ajm.ligtenberg.obc.acta@med.vu.nl
authors.forename: T J
authors.initials: TJ
authors.lastname: Ligtenberg
authors.forename: F J
authors.initials: FJ
authors.lastname: Bikker
authors.forename: J
authors.initials: J
authors.lastname: Groenink
authors.forename: I
authors.initials: I
authors.lastname: Tornoe
authors.forename: R
authors.initials: R
authors.lastname: Leth-Larsen
authors.forename: E C
authors.initials: EC
authors.lastname: Veerman
authors.forename: A V
authors.initials: AV
authors.lastname: Nieuw Amerongen
authors.forename: U
authors.initials: U
authors.lastname: Holmskov
mesh_terms: D000373:Agglutinins / Q000737:chemistry / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000737:chemistry; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D015894:Genome, Human; D006801:Humans; D008168:Lung / Q000378:metabolism* / Q000382:microbiology; D008565:Membrane Proteins; D010306:Parotid Gland / Q000378:metabolism; D011485:Protein Binding; D037663:Pulmonary Surfactant-Associated Protein D / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D012463:Saliva / Q000378:metabolism*; D051122:Scavenger Receptors, Class B; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013295:Streptococcus mutans / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
chemical_list: D000373:Agglutinins; D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; C108174:DMBT1 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D025521:Tumor Suppressor Proteins; C116303:glycoprotein 340