Publisher Summary Lectins play an important role in the development of immunology. Lectins also find application in serological laboratories for typing blood and determining secretor status, separating leucocytes from erythrocytes, and agglutinating cells from blood in the preparation of plasma. They serve as reagents for the detection, isolation, and characterization of carbohydrate-containing macromolecules, including blood-group antigens. In their interaction with saccharides, lectins serve as models for carbohydrate-specific antibodies, with the important advantage to purify lectins in gram quantities. Lectins are classified according to their carbohydrate-binding specificity that includes D-mannose(D-glucose)-binding lectins and 2-acetamido-2-deoxy-D-glucose-binding lectins. The chapter considers only those lectins that have been purified to homogeneity, and studied with regard to their biophysical, biochemical, and carbohydrate-binding specificity. The chapter also describes the cell-binding and biological properties of lectins. The chapter concludes with the description of several glycopeptide structures showing the carbohydrate-binding loci with which various lectins interact.

The lectins : carbohydrate-binding proteins of plants and animals

Chemical Diversity in the Sialic Acids and Related α-Keto Acids: An Evolutionary Perspective

A critical physiological role of zinc in the structure and function of biomembranes.

The innate immune response of finfish--a review of current knowledge.

Noncellular nonspecific defence mechanisms of fish

The complete amino acid sequence of sialic acid binding lectin from frog (Rana catesbeiana) egg is presented. The 111-residue sequence was determined by the analysis of peptides generated by digestion of the S-carboxymethylated protein with Achromobacter protease I, chymotrypsin, or cyanogen bromide. The sequence is unique and not homologous to any known protein sequence. The protein may represent a new type of lectin.

Amino acid sequence of sialic acid binding lectin from frog (Rana catesbeiana) eggs

Two frog egg lectins [Rana catesbeiana lectin (SBL-C) and Rana japonica lectin] preferentially agglutinate a large variety of human and animal tumor cells but not blood cells, lymphocytes, or fibroblasts. These lectins belong to the superfamily of pyrimidine base-specific RNases. The two lectins bound to a heparin-Sepharose column and were eluted from the column by an increase of NaCl molarity. Both their tumor cell-agglutinating activity and RNase activity were inhibited by heparin, and also by polyamines, such as spermine. Both lectins inhibited P388 leukemia cell proliferation. The inhibitory activity of SBL-C was blocked by addition of heparin. SBL-C inhibited protein synthesis by P388 cells, but RNase A did not. No lectin-induced antiproliferative effect was observed after sialidase treatment of cells. The antiproliferative activity of SBL-C was also inhibited by ammonium chloride treatment. These results suggest that internalization of the lectins by lectin receptor (sialoglycoconjugate)-mediated endocytosis is followed by cell death due to inhibition of protein synthesis. Administration of SBL-C i.p. delayed time to death in mice receiving i.p. transplants of Sarcoma 180 and Mep II cells.

https://cancerres.aacrjournals.org/content/canres/54/4/920.full.pdf

Inhibition of Cell Proliferation by Rana catesbeiana and Rana japonica Lectins Belonging to the Ribonuclease Superfamily

A lectin isolated from Rana catesbeiana eggs preferentially agglutinates a large variety of human and animal tumor cells but not normal red blood cells, lymphocytes, or fibroblasts. The phenomenon correlates with a higher binding activity of the lectin with tumor cells. Chemical and physical analysis of the purified lectin indicates that the lectin is a low molecular weight basic polypeptide with five intrachain disulfide bonds. Its agglutination of tumor cells was abolished by blocking the amino group. The lectin strongly binds with a large variety of tumor cells but binds only minimally with fibroblasts, lymphocytes, and erythrocytes. Tumor cell agglutination induced by this lectin was strongly inhibited by submaxillary mucin, to a lesser degree by fetuin and keratan sulfate, and not at all by less-sialylated glycoproteins, such as transferrin. Inhibition by mucin or fetuin was greatly reduced by desialylation of glycoprotein with sialidase. Treatment of tumor cells with sialidase greatly reduced the lectin-dependent agglutination, and the sialidase-dependent reduction of tumor cell agglutination was inhibited by the sialidase inhibitor 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. However, tumor cell agglutination was not inhibited by chondroitin sulfates or hyaluronic acid. Thus, the lectin-dependent tumor cell agglutination is due to a high density of sialic acid at the cell surface. The receptor glycoprotein that interacts with this lectin was demonstrated in the detergent-insoluble fraction of a variety of tumor cells by sodium dodecyl sulfate:polyacrylamide gel electrophoresis, followed by Western blotting with lectin and anti-lectin antibodies. The presence of a common high molecular weight lectin-binding glycoprotein in various tumor cells was demonstrated.

http://cancerres.aacrjournals.org/content/canres/47/18/4877.full.pdf

Isolation and Characterization of Rana catesbeiana Lectin and Demonstration of the Lectin-binding Glycoprotein of Rodent and Human Tumor Cell Membranes

Two lectins with RNase activity obtained from eggs of Rana catesbeiana and R. japonica and RNase obtained from R. catesbeiana liver show 65-83% protein homology. The base specificity of these frog proteins was studied with 8 dinucleoside phosphates as substrates and 8 nucleotides as inhibitors. The base specificities of the B1 and B2 sites of these proteins are U greater than C and G greater than U greater than A, C, respectively. The three frog proteins are more resistant than RNase A to heat treatment, guanidine-HCl and pH-induced denaturation; i.e., they retain their native conformation up to at least 70 degrees C at pH 7.5. Differences in stability and base specificity among RNase A and the three frog proteins are discussed in relation to the primary structures. Although the two lectins agglutinate tumor cells (e.g., Ehrlich, S-180 and AH109A ascites carcinoma cells), the liver RNase has no such activity. Agglutination of AH109A cells by the two lectins is inhibited by nucleotides. Our results indicate that the agglutination sites are not identical with, but are related to, the active sites of the three frog proteins.

Comparative base specificity, stability, and lectin activity of two lectins from eggs of Rana catesbeiana and R. japonica and liver ribonuclease from R. catesbeiana.

The complete amino acid sequence and the location of disulfide bonds of a lectin from Japanese frog (Rana japonica) eggs, which specifically agglutinates transformed cells, are presented. The sequence was determined by analysis of peptides generated by digestion of the S-carboxyamidomethylated protein with Achromobacter protease I, or chymotrypsin, and by chemical cleavage with BNPS-skatole or cyanogen bromide. The lectin is a single-chain protein consisting of 111 residues, with a pyroglutamyl residue at the amino terminus. Four disulfide bonds link half-cystinyl residue 19 to 72, 34 to 82, 52 to 97, and 94 to 111. The sequence and the location of the disulfide bonds are highly homologous to those of bull frog (Rana catesbeiana) egg S-lectin. They are also homologous to human angiogenin, a tumor angiogenesis factor, and a family of pancreatic ribonucleases.

Hiroaki Kawauchi

Papers

Amino acid sequence of sialic acid binding lectin from frog (Rana catesbeiana) eggs

Inhibition of Cell Proliferation by Rana catesbeiana and Rana japonica Lectins Belonging to the Ribonuclease Superfamily

Isolation and Characterization of Rana catesbeiana Lectin and Demonstration of the Lectin-binding Glycoprotein of Rodent and Human Tumor Cell Membranes

Comparative base specificity, stability, and lectin activity of two lectins from eggs of Rana catesbeiana and R. japonica and liver ribonuclease from R. catesbeiana.

Amino acid sequence of a lectin from Japanese frog (Rana japonica) eggs.