Disease relevance of CGN1

• In haemagglutination inhibition (HI) of influenza A virus, although native and recombinant conglutinin showed similar levels of HI activity, the recombinant SP-D was unable to inhibit haemagglutination, even at a concentration approx. 120-fold that of the native SP-D [1].
• In contrast, conglutinin was the most potent of the three collectins against influenza virus A/HKx31 [2].
• In order to elucidate the biological role of the collagen-like domain, a recombinant partial conglutinin lacking this collagen-like domain was produced in an Escherichia coli system and its biological activities were examined [3].
• The trimer, although lacking the N-terminal and collagen regions of the native conglutinin, showed the same binding carbohydrate specificities as the native molecule, for the complement fragment C3b and for lipopolysaccharides derived from Gram-negative bacteria [4].
• In vitro experiments with T-lymphoblastoid CEM cells revealed that conglutinin-like protein abolishes infection by HIV-1; a 50% cytoprotective concentration of 23.9 micrograms/ml was measured [5].

High impact information on CGN1

• Generation of three different fragments of bound C3 with purified factor I or serum. II. Location of binding sites in the C3 fragments for factors B and H, complement receptors, and bovine conglutinin [6].
• On the basis of identical collagen domain structures, we suggest that conglutinin and bovine surfactant protein-D evolved from a gene duplication event occurring in Bovidae after divergence from other mammals [7].
• The N-terminal sequence (27 amino acids) showed 56% identity with bovine SP-D and 44% identity to bovine conglutinin [8].
• Bound conglutinin was eluted with GlcNAc, and then the 43-kDa lectin, together with mannan-binding protein (MBP), was eluted with mannose [8].
• By using IAV strains with specific variations in glycosylation of the hemagglutinin molecule, we showed these effects to be mediated by binding of conglutinin to high mannose carbohydrate attachments on the viral hemagglutinin [9].

Chemical compound and disease context of CGN1

• Two distinct serum mannose-binding lectins function as beta inhibitors of influenza virus: identification of bovine serum beta inhibitor as conglutinin [10].
• These results indicate that conglutinin may inhibit the infection with HIV-1 through its interaction with the viral envelope glycoprotein [11].

Biological context of CGN1

• We report the complete amino acid sequence of bovine conglutinin obtained by structural characterization of peptides derived from the protein by various chemical and enzymatic fragmentation methods [12].
• The noncollagenous COOH domain of conglutinin, on the other hand, contains a carbohydrate recognition domain which shares substantial sequence homology with C-type animal lectins [12].
• The results presented here strongly indicate that receptor-ligand interaction is mediated via the N-terminal region of conglutinin, consistent with the earlier proposal for the binding site [13].
• However, the presence of 108 bp exons in the gene encoding the collagen-like domain was a characteristic of conglutinin [14].
• In the promoter region of the gene, several putative consensus sequences that may be involved in the expression of conglutinin were identified [14].

Anatomical context of CGN1

• Pre-incubation of IAV with conglutinin markedly potentiated human neutrophil hydrogen peroxide production in response to the virus [9].
• Membrane complement receptor type three (CR3) has lectin-like properties analogous to bovine conglutinin as functions as a receptor for zymosan and rabbit erythrocytes as well as a receptor for iC3b [15].
• The mammalian C-type lectin family includes conglutinin, mannose-binding protein, and surfactant proteins A and D. These lectins may be important constituents of the initial host response to IAV, by inhibiting IAV infectivity directly, causing viral aggregation, and acting as opsonins to enhance phagocyte responses to the virus [9].
• Human leukocyte complement receptor type three (CR3) was shown to be lectin-like and to resemble bovine serum conglutinin (K) in that it bound to both iC3b and unopsonized yeast (Saccharomyces cerevisiae), and was inhibited by EDTA or N-acetyl-D-glucosamine (NADG) [15].
• Although its physiologic function is unknown, conglutinin is known to bind, in the presence of calcium, to yeast cell walls and to the solid-phase-inactivated third component of complement [16].

Associations of CGN1 with chemical compounds

• Conglutinin has the greatest sequence similarity with mannose-binding proteins and pulmonary surfactant-associated proteins [12].
• Bovine conglutinin is a Ca(2+)-dependent serum lectin specific for N-acetylglucosamine [14].
• Inhibition experiments with D-mannose oligosaccharides establish that conglutinin recognises terminal alpha 1----2 mannobiosyl units present in the glycopeptide of the alpha-chain of the complement component C3b [17].
• When EAC43b were treated with heated serum in EDTA, reactivity with bovine conglutinin appeared rapidly, even at 0 degrees C, and almost simultaneously with the loss of C3b rosetting capacity [18].
• From these results it is deduced that the reactivity of conglutinin with the complement glycopeptide iC3b rather than the intact glycoprotein C3 is due to the oligosaccharide accessibility rendered by proteolysis in the complement cascade [19].

Physical interactions of CGN1

• Association of C1q- and conglutinin-binding immune complexes with high consumption of alpha-2-macroglobulin in synovial fluids of patients with rheumatoid arthritis [20].

Other interactions of CGN1

• Since SP-D appears to be a lung-specific protein, it seems probable that the liver is the primary site of synthesis of conglutinin [21].
• Since structural similarity often associates with common functionality, some of SP-D's effector mechanisms may apply to conglutinin, CL-43 and CL-46--and vice versa [22].
• Northern blot or immunocytochemical analysis confirm biosynthesis of bovine collectins mainly in the liver (conglutinin, CL-43) and in the thymus (CL-46) [23].
• Development of enzyme-linked immunosorbent assays for conglutinin, mannan-binding protein, and serum amyloid-P component in bovine sera [24].
• Effects of preventing periparturient hypocalcemia in cows by parathyroid hormone administration on hematology, conglutinin, immunoglobulin, and shedding of Staphylococcus aureus in milk [25].

Analytical, diagnostic and therapeutic context of CGN1

• Northern blot analysis of bovine tissues showed that conglutinin mRNA of about 1.5 kb is expressed in the liver and also slightly in the lung [26].
• Southern blot analysis of total bovine genomic DNA indicated that there is only one copy of the gene encoding bovine conglutinin [26].
• A 912 bp bovine cDNA fragment encoding bovine conglutinin was amplified by the RT-PCR technique. cDNA clones encoding the bovine conglutinin were isolated from a bovine liver cDNA library using a specific probe obtained from the PCR product [26].
• In turn, a cosmid containing the entire bovine CGN1 was used with fluorescence in situ hybridization to sublocalize this gene to cattle Chromosome (Chr) (BTA) 28 band 18 [27].
• To date, conglutinin, which appears to play an important role in defence mechanisms, has been fully described, by protein sequence analysis, only in the bovine system [21].

References