SMART: CLECT domain annotation

CLECT C-type lectin (CTL) or carbohydrate-recognition domain (CRD)

SMART accession number:	SM00034
Description:	Many of these domains function as calcium-dependent carbohydrate binding modules.
Interpro abstract (IPR001304):	Lectins occur in plants, animals, bacteria and viruses. Initially described for their carbohydrate-binding activity (PUBMED:14533786), they are now recognised as a more diverse group of proteins, some of which are involved in protein-protein, protein-lipid or protein-nucleic acid interactions (PUBMED:12223269). There are at least twelve structural families of lectins: C-type lectins, which are Ca+-dependent. S-type (galectins), a widespread family of glycan-binding proteins (PUBMED:17497244). I-type, which have an immunoglobulin-like fold and can recognise sialic acids, other sugars and glycosaminoglycans (PUBMED:12223277). P-type, which bind phosphomannosyl receptors (PUBMED:12223278). Pentraxins (PUBMED:16343883). (Trout) egg lectins. Calreticulin and calnexin, which act as molecular chaperones of the endoplasmic reticulum (PUBMED:17072021). ERGIC-53 and VIP-36 (PUBMED:7876089). Discoidins (PUBMED:17702679). Eel aggutinins (fucolectins) (PUBMED:10924498). Annexin lectins (PUBMED:15813707). Fibrinogen-type lectins, which includes ficolins, tachylectins 5A and 5B, and Limax flavus (Spotted garden slug) agglutinin (these proteins have clear distinctions from one another, but they share a homologous fibrinogen-like domain used for carbohydrate binding). Also unclassified orphan lectins, including amphoterin, Cel-II, complement factor H, thrombospondin, sailic acid-binding lectins, adherence lectin, and cytokins (such as tumour necrosis factor and several interleukins). C-type lectins can be further divided into seven subgroups based on additional non-lectin domains and gene structure: (I) hyalectans, (II) asialoglycoprotein receptors, (III) collectins, (IV) selectins, (V) NK group transmembrane receptors, (VI) macrophage mannose receptors, and (VII) simple (single domain) lectins (PUBMED:15476922). Therefore, lectins are a diverse group of proteins, both in terms of structure and activity. Carbohydrate binding ability may have evolved independently and sporadically in numerous unrelated families, where each evolved a structure that was conserved to fulfil some other activity and function. In general, animal lectins act as recognition molecules within the immune system, their functions involving defence against pathogens, cell trafficking, immune regulation and the prevention of autoimmunity (PUBMED:14519388).
GO function:	binding (GO:0005488)
Family alignment:	View or

There are 5670 CLECT domains in 4204 proteins in SMART's nrdb database.

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Evolution (species in which this domain is found)
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This tree shows only several representative species. The complete taxonomic breakdown of all proteins with CLECT domain is also avaliable.

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Go to specific node: Anopheles gambiae, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens, Mus musculus, Rattus norvegicus, Takifugu rubripes
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
- Elgavish S, Shaanan B
- Lectin-carbohydrate interactions: different folds, common recognition principles.
- Trends Biochem Sci. 1997; 22: 462-7
- Display abstract
- Lectins can be found in many organisms and are involved in a multitude of cellular processes that depend on specific recognition of complex carbohydrates. The stereochemical principles underlying the recognition process have been the subject of extensive biochemical and structural studies. When examined from the viewpoint of the bound sugar, the structural information accumulated so far on lectins and other proteins that are specific to galactose and glucose (or mannose), provides suggestive evidence for distinct ligand-dependent distribution of hydrogen-bond partners in the combining site.
- Weis WI, Drickamer K
- Structural basis of lectin-carbohydrate recognition.
- Annu Rev Biochem. 1996; 65: 441-73
- Display abstract
- Lectins are responsible for cell surface sugar recognition in bacteria, animals, and plants. Examples include bacterial toxins; animal receptors that mediate cell-cell interactions, uptake of glycoconjugates, and pathogen neutralization; and plant toxins and mitogens. The structural basis for selective sugar recognition by members of all of these groups has been investigated by x-ray crystallography. Mechanisms for sugar recognition have evolved independently in diverse protein structural frameworks, but share some key features. Relatively low affinity binding sites for monosaccharides are formed at shallow indentations on protein surfaces. Selectivity is achieved through a combination of hydrogen bonding to the sugar hydroxyl groups with van der Waals packing, often including packing of a hydrophobic sugar face against aromatic amino acid side chains. Higher selectivity of binding is achieved by extending binding sites through additional direct and water-mediated contacts between oligosaccharides and the protein surface. Dramatically increased affinity for oligosaccharides results from clustering of simple binding sites in oligomers of the lectin polypeptides. The geometry of such oligomers helps to establish the ability of the lectins to distinguish surface arrays of polysaccharides in some instances and to crosslink glycoconjugates in others.
- Holmskov U, Malhotra R, Sim RB, Jensenius JC
- Collectins: collagenous C-type lectins of the innate immune defense system.
- Immunol Today. 1994; 15: 67-74
- Display abstract
- Collectins are humoral lectins found in mammals and birds. They are oligomers whose subunits comprise three polypeptide chains each containing a collagenous section and a C-terminal lectin domain. They are related structurally and functionally to the first component of the classical complement pathway, C1q, and seem to serve important roles in innate immunity through opsonization and complement activation. The lectin domains bind carbohydrates on microorganisms, while the collagenous regions are ligands for the collectin receptor on phagocytes and also mediate C1q-independent activation of the classical complement pathway.
- Drickamer K
- Two distinct classes of carbohydrate-recognition domains in animal lectins.
- J Biol Chem. 1988; 263: 9557-60
Metabolism (metabolic pathways involving proteins which contain this domain)

Structure (3D structures containing this domain)

3D Structures of CLECT domains in PDB

PDB code	Main view	Title
1afa		Structural basis of galactose recognition in c-type animal lectins
1afb		Structural basis of galactose recognition in c-type animal lectins
1afd		Structural basis of galactose recognition in c-type animal lectins
1b08		Lung surfactant protein d (sp-d) (fragment)
1b6e		Human cd94
1bch		Mannose-binding protein-a mutant (qpdwgh) complexed with n- acetyl-d-galactosamine
1bcj		Mannose-binding protein-a mutant (qpdwghv) complexed with n- acetyl-d-galactosamine
1bj3		Crystal structure of coagulation factor ix-binding protein (ix-bp) from venom of habu snake with a heterodimer of c- type lectin domains
1buu		One ho3+ form of rat mannose-binding protein a
1bv4		Apo-mannose-binding protein-c
1byf		Structure of tc14; a c-type lectin from the tunicate polyandrocarpa misakiensis
1c3a		Crystal structure of flavocetin-a from the habu snake venom, a novel cyclic tetramer of c-type lectin-like heterodimers
1dv8		Crystal structure of the carbohydrate recognition domain of the h1 subunit of the asialoglycoprotein receptor
1e87		Human cd69-trigonal form
1e8i		Human cd69-tetragonal form
1egg		Structure of a c-type carbohydrate-recognition domain (crd- 4) from the macrophage mannose receptor
1egi		Structure of a c-type carbohydrate-recognition domain (crd- 4) from the macrophage mannose receptor
1esl		Insight into e-selectin(slash)ligand interaction from the crystal structure and mutagenesis of the lec(slash)egf domains
1fif		N-acetylgalactosamine-selective mutant of mannose-binding protein-a (qpdwg-hdrpy)
1fih		N-acetylgalactosamine binding mutant of mannose-binding protein a (qpdwg-hdrpy), complex with n-acetylgalactosamine
1fm5		Crystal structure of human cd69
1fvu		Crystal structure of botrocetin
1g1q		Crystal structure of p-selectin lectin/egf domains
1g1r		Crystal structure of p-selectin lectin/egf domains complexed with slex
1g1s		P-selectin lectin/egf domains complexed with psgl-1 peptide
1g1t		Crystal structure of e-selectin lectin/egf domains complexed with slex
1gz2		Crystal structure of the ovocleidin-17 a major protein of the gallus gallus eggshell calcified layer.
1h8u		Crystal structure of the eosinophil major basic protein at 1.8a: an atypical lectin with a paradigm shift in specificity
1hq8		Crystal structure of the murine nk cell-activating receptor nkg2d at 1.95 a
1htn		Human tetranectin, a trimeric plasminogen binding protein with an alpha-helical coiled coil
1hup		Human mannose binding protein carbohydrate recognition domain trimerizes through a triple alpha-helical coiled- coil
1hyr		Crystal structure of human mica in complex with natural killer cell receptor nkg2d
1ijk		The von willebrand factor mutant (i546v) a1 domain- botrocetin complex
1iod		Crystal structure of the complex between the coagulation factor x binding protein from snake venom and the gla domain of factor x
1ixx		Crystal structure of coagulation factors ix/x-binding protein (ix/x-bp) from venom of habu snake with a heterodimer of c-type lectin domains
1j34		Crystal structure of mg(ii)-and ca(ii)-bound gla domain of factor ix complexed with binding protein
1j35		Crystal structure of ca(ii)-bound gla domain of factor ix complexed with binding protein
1ja3		Crystal structure of the murine nk cell inhibitory receptor ly-49i
1jsk		Crystal structure of murine nk cell ligand rae-1 beta in complex with nkg2d
1jwi		Crystal structure of bitiscetin, a von willeband factor- dependent platelet aggregation inducer.
1jzn		Crystal structure of a galactose-specific c-type lectin
1k9i		Complex of dc-sign and glcnac2man3
1k9j		Complex of dc-signr and glcnac2man3
1kcg		Nkg2d in complex with ulbp3
1kg0		Structure of the epstein-barr virus gp42 protein bound to the mhc class ii receptor hla-dr1
1kmb		Selectin-like mutant of mannose-binding protein a
1kwt		Rat mannose binding protein a (native, mpd)
1kwu		Rat mannose binding protein a complexed with a-me-man
1kwv		Rat mannose binding protein a complexed with a-me-glcnac
1kww		Rat mannose protein a complexed with a-me-fuc.
1kwx		Rat mannose protein a complexed with b-me-fuc.
1kwy		Rat mannose protein a complexed with man-a13-man.
1kwz		Rat mannose protein a (h189v) complexed with man-a13-man
1kx0		Rat mannose protein a (h189v i207v) complexed with man-a13- man
1kx1		Rat mannose protein a complexed with man6-glcnac2-asn
1kza		Complex of mbp-c and man-a13-man
1kzb		Complex of mbp-c and trimannosyl core
1kzc		Complex of mbp-c and high-affinity linear trimannose
1kzd		Complex of mbp-c and glcnac-terminated core
1kze		Complex of mbp-c and bivalent man-terminated glycopeptide
1lit		Human lithostathine
1mpu		Crystal structure of the free human nkg2d immunoreceptor
1msb		Structure of the calcium-dependent lectin domain from a rat mannose-binding protein determined by mad phasing
1muq		X-ray crystal structure of rattlesnake venom complexed with thiodigalactoside
1oz7		Crystal structure of echicetin from the venom of indian saw- scaled viper (echis carinatus) at 2.4 resolution
1p1z		X-ray crystal structure of the lectin-like natural killer cell receptor ly-49c bound to its mhc class i ligand h-2kb
1p4l		Crystal structure of nk receptor ly49c mutant with its mhc class i ligand h-2kb
1pw9		High resolution crystal structure of an active recombinant fragment of human lung surfactant protein d
1pwb		High resolution crystal structure of an active recombinant fragment of human lung surfactant protein d with maltose
1qdd		Crystal structure of human lithostathine to 1.3 a resolution
1qo3		Complex between nk cell receptor ly49a and its mhc class i ligand h-2dd
1r13		Carbohydrate recognition and neck domains of surfactant protein a (sp-a)
1r14		Carbohydrate recognition and neck domains of surfactant protein a (sp-a) containing samarium
1rdi		Mannose-binding protein, subtilisin digest fragment complex with alpha-methyl-l-fucopyranoside
1rdj		Mannose-binding protein, subtilisin digest fragment complex with beta-methyl-l-fucopyranoside
1rdk		Mannose-binding protein, subtilisin digest fragment complex with d-galactose
1rdl		Mannose-binding protein, subtilisin digest fragment complex with alpha-methyl-d-mannopyranoside (0.2 m)
1rdm		Mannose-binding protein, subtilisin digest fragment complex with alpha-methyl-d-mannopyranoside (1.3 m)
1rdn		Mannose-binding protein, subtilisin digest fragment complex with alpha-methyl-d-n-acetylglucosaminide
1rdo		Mannose-binding protein, subtilisin digest fragment
1rjh		Structure of the calcium free form of the c-type lectin- like domain of tetranectin
1rtm		Trimeric structure of a c-type mannose-binding protein
1sb2		High resolution structure determination of rhodocetin
1sl4		Crystal structure of dc-sign carbohydrate recognition domain complexed with man4
1sl5		Crystal structure of dc-sign carbohydrate recognition domain complexed with lnfp iii (dextra l504).
1sl6		Crystal structure of a fragment of dc-signr (containg the carbohydrate recognition domain and two repeats of the neck) complexed with lewis-x.
1t8c		Structure of the c-type lectin domain of cd23
1t8d		Structure of the c-type lectin domain of cd23
1tdq		Structural basis for the interactions between tenascins and the c-type lectin domains from lecticans: evidence for a cross-linking role for tenascins
1tlg		Structure of a tunicate c-type lectin complexed with d- galactose
1tn3		The c-type lectin carbohydrate recognition domain of human tetranectin
1u0n		The ternary von willebrand factor a1-glycoprotein ibalpha- botrocetin complex
1u0o		The mouse von willebrand factor a1-botrocetin complex
1uex		Crystal structure of von willebrand factor a1 domain complexed with snake venom bitiscetin
1ukm		Crystal structure of ems16, an antagonist of collagen receptor integrin alpha2beta1 (gpia/iia)
1umr		Crystal structure of the platelet activator convulxin, a disulfide linked a4b4 cyclic tetramer from the venom of crotalus durissus terrificus
1uos		The crystal structure of the snake venom toxin convulxin
1uv0		Pancreatitis-associated protein 1 from human
1v4l		Crystal structure of a platelet agglutination factor isolated from the venom of taiwan habu (trimeresurus mucrosquamatus)
1v7p		Structure of ems16-alpha2-i domain complex
1wk1		Solution structure of lectin c-type domain derived from a hypothetical protein from c. elegans
1wmy		Crystal structure of c-type lectin cel-i from cucumaria echinata
1wmz		Crystal structure of c-type lectin cel-i complexed with n- acetyl-d-galactosamine
1wt9		Crystal structure of aa-x-bp-i, a snake venom protein with the activity of binding to coagulation factor x from agkistrodon acutus
1x2t		Crystal structure of habu ix-bp at ph 6.5
1x2w		Crystal structure of apo-habu ix-bp at ph 4.6
1xar		Crystal structure of a fragment of dc-signr (containing the carbohydrate recognition domain and two repeats of the neck).
1xph		Structure of dc-signr and a portion of repeat domain 8
1y17		Crystal structure of aa-x-bp-ii, a snake venom protein with the activity of binding to coagulation factor x from agkistrodon acutus
1ypo		Human oxidized low density lipoprotein receptor lox-1 p3 1 space group
1ypq		Human oxidized low density lipoprotein receptor lox-1 dioxane complex
1ypu		Human oxidized low density lipoprotein receptor lox-1 c2 space group
1ytt		Yb substituted subtilisin fragment of mannose binding protein-a (sub-mbp-a), mad structure at 110k
1yxj		Crystal structure of human lectin-like oxidized low-density lipoprotein receptor 1 (lox-1) at low ph
1yxk		Crystal structure of human lectin-like oxidized low-density lipoprotein receptor 1 (lox-1) disulfide-linked dimer
2afp		The solution structure of type ii antifreeze protein reveals a new member of the lectin family
2b6b		Cryo em structure of dengue complexed with crd of dc-sign
2bpd		Structure of murine dectin-1
2bpe		Structure of murine dectin-1
2bph		Structure of murine dectin-1
2brs		Embp heparin complex
2c6u		Crystal structure of human clec-2 (clec1b)
2cl8		Dectin-1 in complex with beta-glucan
2e3x		Crystal structure of russell's viper venom metalloproteinase
2ggu		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with maltotriose
2ggx		Crystal structure of the trimer neck and carbohydrate recognition domain of human surfactant protein d in complex with p-nitrophenyl maltoside
2go0		Nmr solution structure of human pancreatitis-associated protein
2h2r		Crystal structure of the human cd23 lectin domain, apo form
2h2t		Cd23 lectin domain, calcium 2+-bound
2it5		Crystal structure of dcsign-crd with man6
2it6		Crystal structure of dcsign-crd with man2
2kmb		Complex of 3'-neuac-lewis-x with a selectin-like mutant of mannose-binding protein a
2msb		Structure of a c-type mannose-binding protein complexed with an oligosaccharide
2orj		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with n-acetyl mannosamine
2ork		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with inositol-1-phosphate
2os9		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with myoinositol
2ox8		Human scavenger receptor c-type lectin carbohydrate- recognition domain.
2ox9		Mouse scavenger receptor c-type lectin carbohydrate- recognition domain.
2py2		Structure of herring type ii antifreeze protein
2ria		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with d-glycero-d-manno-heptose
2rib		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with l-glycero-d-manno-heptose
2ric		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with l-glycero-d-manno-heptopyranosyl-(1-3)-l- glycero-d-manno-heptopyranose
2rid		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with allyl 7-o-carbamoyl-l-glycero-d-manno- heptopyranoside
2rie		Crystal structure of the trimeric neck and carbohydrate recognition domain of human surfactant protein d in complex with 2-deoxy-l-glycero-d-manno-heptose
2vrp		Structure of rhodocytin
2vuv		Crystal structure of codakine at 1.3a resolution
2vuz		Crystal structure of codakine in complex with biantennary nonasaccharide at 1.7a resolution
2zib		Crystal structure analysis of calcium-independent type ii antifreeze protein
3bbs		The carbohydrate recognition domain of langerin reveals high structural similarity with the one of dc-sign but an additional, calcium-independent sugar-binding site
3bc6		The carbohydrate recognition domain of langerin reveals high structural similarity with the one of dc-sign but an additional, calcium-independent sugar-binding site
3bc7		The carbohydrate recognition domain of langerin reveals high structural similarity with the one of dc-sign but an additional, calcium-independent sugar-binding site
3bdw		Human cd94/nkg2a
3bx4
3c22
3c8j		The crystal structure of natural killer cell receptor ly49c
3c8k		The crystal structure of ly49c bound to h-2kb
3cad		Crystal structure of natural killer cell receptor, ly49g
3cck
3cdg		Human cd94/nkg2a in complex with hla-e
3cfw		L-selectin lectin and egf domains
3cii		Structure of nkg2a/cd94 bound to hla-e
3dbz		Human surfactant protein d
3fd4
3ff7
3ff8
3ff9
3g81
3g83
3g84
3g8k
3g8l
3ikn
3ikp
3ikq
3ikr
3kmb		Complex of 3'-sulfo-lewis-x with a selectin-like mutant of mannose-binding protein a
4kmb		Complex of 4'-sulfo-lewis-x with a selectin-like mutant of mannose-binding protein a

Links (links to other resources describing this domain)
BLOCKS C_TYPE_LECTIN_1
PFAM lectin_c
INTERPRO IPR001304
PROSITE CLECT_DOMAIN

BLOCKS	C_TYPE_LECTIN_1
PFAM	lectin_c
INTERPRO	IPR001304
PROSITE	CLECT_DOMAIN