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

The occurrence in nature of erythrocyte-agglutinating proteins has been known since the turn of the 19th century. By the 1960s it became apparent that such proteins also agglutinate other types of cells, and that many of them are sugar-specific. These cell-agglutinating and sugar-specific proteins have been named lectins. Although shown to occur widely in plants and to some extent also in invertebrates, very few lectins had been isolated until the early 1970s, and they had attracted little attention. This attitude changed with the demonstration that lectins are extremely useful tools for the investigation of carbohydrates on cell surfaces, in particular of the changes that the latter undergo in malignancy, as well as for the isolation and characterization of glycoproteins. In subsequent years numerous lectins have been isolated from plants as well as from microorganisms and animals, and during the past two decades the structures of hundreds of them have been established. Concurrently, it was shown that lectins function as recognition molecules in cell-molecule and cell-cell interactions in a variety of biological systems. Here we present a brief account of 100-plus years of lectin research and show how these proteins have become the focus of intense interest for biologists and in particular for the glycobiologists among them.

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History of lectins: from hemagglutinins to biological recognition molecules

The growth response of a population to the resources in a particular environment is used to classify pairs of resources as being either (1) essential, (2) hemi-essential, (3) complementary, (4) perfectly substitutable, (5) antagonistic, or (6) switching. Although nutrition is one important factor determining resource type, the growth response of a population to resources also depends on the interaction between a species' foraging methods and the spatial distribution of the resources. For example, two resources which are nutritionally perfectly substitutable may be operationally switching, antagonistic, or complementary because of spatial heterogeneity. A graphical, equilibrium theory of resource competition allows prediction of the outcome of interactions between several consumers for the various classes of resources. The technique requires information on (1) resource type (growth isoclines), (2) resource preference, (3) resource supply processes, and (4) mortality rates for all species. For all resource ...

Resources: A Graphical-Mechanistic Approach to Competition and Predation

Lectins are carbohydrate-binding proteins that bind gly? cans of glycoproteins, glycolipids, or polysaccharides with high affinity (Goldstein and Hayes, 1978). Because of their binding specificity, they have the capability to serve as recognition molecules within a cell, between cells, or be? tween organisms. It is assumed that lectins play fundamental biological roles in plants because they are found in many different species and in many different organs and tissues.

Lectins, lectin genes, and their role in plant defense.

Selected plant lectins have been found to be larvicidal against a number of common insect pests of agricultural crops. In a preferred embodiment, plant resistance to these insects is produced by inserting into the cells of a plant a gene whose expression causes production of one or more of these lectins in larvicidal amounts.

Larvicidal lectins and plant insect resistance based thereon

Black bean (Phaseolus vulgaris) phytohemagglutinin added to the normal diet of a bruchid beetle (Callosobruchus maculatus) that can eat phytohemagglutinin-free cowpeas (Vigna unguiculata) but not P. vulgaris seeds kills the bruchid larvae. Trypsin inhibitors, found in both P. vulgaris and V. unguiculata seeds, have virtually no effect on the bruchid larvae. The conclusion is that a major part of the adaptive significance of phytohemagglutinins in black bean and other legume seeds is to protect them from attack by insect seed predators.

https://science.sciencemag.org/content/sci/192/4241/795.full.pdf

Insecticidal action of the phytohemagglutinin in black beans on a bruchid beetle.

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/23041/0000612.pdf?sequence=1

Harvey B. Juster

Papers

Insecticidal action of the phytohemagglutinin in black beans on a bruchid beetle.

Toxicity of secondary compounds to the seed-eating larvae of the bruchid beetle Callosobruchus maculatus