| lectin | <plant biology> Proteins obtained particularly from the seeds of leguminous plants, but also from many other plant and animal sources, that have binding sites for specific mono or oligosaccharides in cell walls or membranes. They thereby change the physiology of the membrane to cause agglutination, mitosis, or other biochemical changes in the cell. Named originally for the ability of some to selectively agglutinate human red blood cells of particular blood groups. Lectins such as concanavalin A and wheat germ agglutinin are widely used as analytical and preparative agents in the study of glycoproteins. (21 Jun 2000) |
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| C type lectin | <cell biology> One of two classes of lectin produced by animal cells, the other being the S type. The C type lectins require disulphide linked cysteines and Ca ions in order to bind to a specific carbohydrate (c.f. S type lectins). The carbohydrate recognition domain of C type lectins consists of about 130 amino acids which contains 18 invariant residues in a highly conserved pattern. These invariant residues include cysteines which probably form disulphide bonds. So far, all identified C type lectins are extracellular proteins and include both Integral membrane proteins, such as the asialoglycoprotein receptor and soluble proteins. (06 Aug 1998) |
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| potato lectin | <protein> Lectin from the potato, Solanum tuberosum. Binds to N acetyl glucosaminyl residues. (18 Nov 1997) |
| S type lectin | <protein> One of two classes of lectin produced by animal cells. The classification of animal lectins into two classes, the other being the C type, was originally proposed by K.Drickamer. The carbohydrate binding activity of the S type lectins requires their cysteines to have free thiols and does not need divalent cations (c.f. C type lectins). They mostly have molecular masses in the range 14-16 kD and often form dimers and higher oligomers. The carbohydrate recognition domain contains a number of critically conserved amino acids and largely binds to _ galactosides. S type lectins certainly occur as cytoplasmic proteins but the existence of extracellular S type lectins is still a matter of debate. (18 Nov 1997) |