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Other Related Information: Lectins and Sugar chains

 

Lectin is defined by Goldstein ¹⁾ et al. As follows.

• A glyco-binding protein or glycoprotein other than the product of an immune response that aggregates cells or complex carbohydrates.
• It has two or more binding sites and can aggregate animal and plant cells.
• Aggregation is specifically blocked by monosaccharides or oligosaccharides. Generally, lectin is used as a general term for substances having specific binding activity to sugar among proteins or glycoproteins existing in plants, animals, microorganisms, etc.

         References
         1) Goldstein, IJ, Hughes, RC, Monsigny, M., Osawa, T., and Sharon, N., Nature.285,66 (1980)

Definition of lectins

In 1957, O. Mäkelä classified them into 4 groups according to the coordination of the hydroxyl groups at the C-3 and C-4 positions of the sugar (Table 1). Lectins classified in the 4th county have not been found yet. Recently, the primary structure of lectins has been analyzed, and classification based on that structure (classification by family) has also been performed (Table 2).

Table 1 Classification of lectins based on monosaccharide recognition in Mäkelä

Classification of Mäkelä	origin	Lectin trivial name	Sugar binding specificity	My Togen activity
Fuc	Gorse	UEA-I	α-L-Fuc	-
Gal GalNAc	Soybean Peanuts Ricinus castor (Ricinus communis) Dorikosumame Mushroom Green beans	SBA PNA RCA120 DBA ABA PHA-E PHA-L	α-GalNAc> β-GalNAc β-Gal β-Gal α-GalNAc Gal β1-3GalNAc GalNAc GalNAc	＋ ± － － ＋
D-Man D-Glc D-GlcNAc	Sword bean pea lentil lentil broad bean Pokeweed potato wheat germ gorse	Con A PSA LCA VFA PWM STA WGA UEA-II	α-Man ＞ α-Glc α-Man ＞ α-Glc α-Man ＞ α-Glc α-Man ＞ α-Glc GlcNAcβ1-4GlcNAc GlcNAcβ1-4GlcNAc GlcNAcβ1-4GlcNAc GlcNAcβ1-4GlcNAc	＋ ＋ ＋ ＋ ＋ ± －
L-Glc L-Man	-	-	-	-

Table 2 Classification of lectins by family 

Family (biological distribution)	Sugar specificity	Main lectins
Leguminosae Lectin L-type lectin (plant)	Man Gal Sia Fuc	DSA PHA SBA UEA-I MAM DBA ConA ECA PSA
Monocot lectin M-type lectin (plant)	Mab	GNA HHA ASA
R-type lectin (animals and plants)	Man Gal Sia Xyl	RCA 120 SSA SNA

Application of lectins

The table below shows the involvement of diseases and sugar chains. Recently, many glycoproteins and glycolipids that can be used as tumor markers have been found. These are those produced directly by the cancer cells themselves or those produced by surrounding cells due to the influence of the cancer cells, and their quantitative or qualitative fluctuations are applied to diagnosis. For example, α-fetoprotein (AFP) increases significantly with liver cancer, so quantitative changes have been used for diagnosis for some time, but recently, by investigating qualitative changes, "changes in sugar chains". , It is possible to detect canceration at an early stage. In various diseases such as cancer, the discovery of new markers and the development of diagnostic methods using them are eagerly desired and are being actively researched. 

Diseases involving sugar chains	Markers and targets	Change	Application
Liver disease, liver cancer	α-fetoprotein N-type sugar chain ^1)	Increased fucosylated sugar chain Increased	Diagnosis by LCA ^3) 4) 5)
		LCA binding rate ^2)
	Transferrin N-type sugar chain	Increase in Lex antigen sugar chain ^6)
		Increase in AAL binding rate ^7)
	γGTP N-type sugar chain	Increased branching ^8)	Early diagnosis of cancer
		Increased lactosamine structure
	Cholinesterase N-type sugar chain	Fucose α1-3 increase ^9) 10)	Diagnosis by AAL
Alcoholic liver disease	Transferrin N-type sugar chain	Decrease / disappear ^11) 12)
Villous cancer	hCG N-type sugar chain	Changes in branching ^13) 14)	Differentiation between good and malignant
Rectal cancer	CEA N-type sugar chain ^15) 16)	Type I decreased, type II increased,	Prognosis diagnosis
		high mannose type increased
Lung cancer	Lactic sugar chain antigen	Increased sialyl Lea and Lex ^17)
	ganglioside	GM2 expression ^18)
Stomach cancer, large intestine cancer	Glycolipids ^19)
Pancreatic cancer	CA19-9 etc.	Increase in sialyl Lea ^20)
	Haptoglobin ^21)	Increased fucosylated sugar chains
Kidney cancer, bladder cancer	Glycolipids	Increase in CDH ^22)
Endometrial cancer	Blood group substance	Expression of H-type sugar chains	Snooping on UEA, PNA23 ^)
Prostate cancer	PSA
Ovarian cancer	CA125		Diagnosis by WGA ^24)
Thyroid cancer	Thyroglobulin		Diagnosis by Con A ^25)
Myeloma	IgG N type sugar chain	Decrease in galactose
Osteosarcoma, osteoporosis	Bone Alkaline Phosphatase Sugar Chain ^26) 27)
Rheumatoid arthritis	IgG N-type sugar chain ^28) 29)	Decrease in galactose ^31)	Diagnosis ^32) 33) 34) 35)
	α1-acid glycoprotein N-type sugar chain ^30)
Pancreatitis	In serum	2-6 Increase in sialyl Lea ^36)
Gastritis, enteritis	Glycolipids of mucosal epithelium
leukemia	Ganglioside		Treatment research ^37) 38)
Neurotic harm	Ganglioside		Therapeutic application
Cataract	Glycolipids	Increase in Lex ^39)
Alzheimer	Glycolipid ^40)	Increase / decrease in the amount of glycolipids

Literature

1. Ohno, M., Nishikawa, A., Taniguchi, N., et al., Int. J. Cancer, 51, 315 (1992)
2. Yamashita, K., Taketa, K., et al., Cancer Res., 53, 1 (1993)
3. Taketa, K., Clinical Laboratory, 39, 1259 (1995)
4. Nikkei Sangyo Shimbun, 1997.6.10., P19
5. Kuwabara, M., Ariyoshi, Y., Inspection and Technology, 27, 443 (1999)

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