glycoside hydrolase family 18 protein such as chitinase, which catalyzes the random endo-hydrolysis of the 1,4-beta-linkages of N-acetylglucosamine in chitin and chitodextrins
The GH18 (glycosyl hydrolase, family 18) type II chitinases hydrolyze chitin, an abundant ...
24-325
1.93e-165
The GH18 (glycosyl hydrolase, family 18) type II chitinases hydrolyze chitin, an abundant polymer of beta-1,4-linked N-acetylglucosamine (GlcNAc) which is a major component of the cell wall of fungi and the exoskeleton of arthropods. Chitinases have been identified in viruses, bacteria, fungi, protozoan parasites, insects, and plants. The structure of the GH18 domain is an eight-stranded beta/alpha barrel with a pronounced active-site cleft at the C-terminal end of the beta-barrel. The GH18 family includes chitotriosidase, chitobiase, hevamine, zymocin-alpha, narbonin, SI-CLP (stabilin-1 interacting chitinase-like protein), IDGF (imaginal disc growth factor), CFLE (cortical fragment-lytic enzyme) spore hydrolase, the type III and type V plant chitinases, the endo-beta-N-acetylglucosaminidases, and the chitolectins. The GH85 (glycosyl hydrolase, family 85) ENGases (endo-beta-N-acetylglucosaminidases) are closely related to the GH18 chitinases and are included in this alignment model.
The actual alignment was detected with superfamily member cd02872:
Pssm-ID: 471972 [Multi-domain] Cd Length: 362 Bit Score: 464.72 E-value: 1.93e-165
This conserved domain family includes a large number of catalytically inactive chitinase-like ...
24-325
1.93e-165
This conserved domain family includes a large number of catalytically inactive chitinase-like lectins (chitolectins) including YKL-39, YKL-40 (HCGP39), YM1, oviductin, and AMCase (acidic mammalian chitinase), as well as catalytically active chitotriosidases. The conserved domain is an eight-stranded alpha/beta barrel fold belonging to the family 18 glycosyl hydrolases. The fold has a pronounced active-site cleft at the C-terminal end of the beta-barrel. The chitolectins lack a key active site glutamate (the proton donor required for hydrolytic activity) but retain highly conserved residues involved in oligosaccharide binding. Chitotriosidase is a chitinolytic enzyme expressed in maturing macrophages, which suggests that it plays a part in antimicrobial defense. Chitotriosidase hydrolyzes chitotriose, as well as colloidal chitin to yield chitobiose and is therefore considered an exochitinase. Chitotriosidase occurs in two major forms, the large form being converted to the small form by either RNA or post-translational processing. Although the small form, containing the chitinase domain alone, is sufficient for the chitinolytic activity, the additional C-terminal chitin-binding domain of the large form plays a role in processing colloidal chitin. The chitotriosidase gene is nonessential in humans, as about 35% of the population are heterozygous and 6% homozygous for an inactivated form of the gene. HCGP39 is a 39-kDa human cartilage glycoprotein thought to play a role in connective tissue remodeling and defense against pathogens.
Pssm-ID: 119351 [Multi-domain] Cd Length: 362 Bit Score: 464.72 E-value: 1.93e-165
This conserved domain family includes a large number of catalytically inactive chitinase-like ...
24-325
1.93e-165
This conserved domain family includes a large number of catalytically inactive chitinase-like lectins (chitolectins) including YKL-39, YKL-40 (HCGP39), YM1, oviductin, and AMCase (acidic mammalian chitinase), as well as catalytically active chitotriosidases. The conserved domain is an eight-stranded alpha/beta barrel fold belonging to the family 18 glycosyl hydrolases. The fold has a pronounced active-site cleft at the C-terminal end of the beta-barrel. The chitolectins lack a key active site glutamate (the proton donor required for hydrolytic activity) but retain highly conserved residues involved in oligosaccharide binding. Chitotriosidase is a chitinolytic enzyme expressed in maturing macrophages, which suggests that it plays a part in antimicrobial defense. Chitotriosidase hydrolyzes chitotriose, as well as colloidal chitin to yield chitobiose and is therefore considered an exochitinase. Chitotriosidase occurs in two major forms, the large form being converted to the small form by either RNA or post-translational processing. Although the small form, containing the chitinase domain alone, is sufficient for the chitinolytic activity, the additional C-terminal chitin-binding domain of the large form plays a role in processing colloidal chitin. The chitotriosidase gene is nonessential in humans, as about 35% of the population are heterozygous and 6% homozygous for an inactivated form of the gene. HCGP39 is a 39-kDa human cartilage glycoprotein thought to play a role in connective tissue remodeling and defense against pathogens.
Pssm-ID: 119351 [Multi-domain] Cd Length: 362 Bit Score: 464.72 E-value: 1.93e-165
The GH18 (glycosyl hydrolases, family 18) type II chitinases hydrolyze chitin, an abundant ...
25-302
3.04e-79
The GH18 (glycosyl hydrolases, family 18) type II chitinases hydrolyze chitin, an abundant polymer of N-acetylglucosamine and have been identified in bacteria, fungi, insects, plants, viruses, and protozoan parasites. The structure of this domain is an eight-stranded alpha/beta barrel with a pronounced active-site cleft at the C-terminal end of the beta-barrel.
Pssm-ID: 119365 [Multi-domain] Cd Length: 322 Bit Score: 244.46 E-value: 3.04e-79
The class V plant chitinases have a glycosyl hydrolase family 18 (GH18) domain, but lack the ...
27-303
4.65e-50
The class V plant chitinases have a glycosyl hydrolase family 18 (GH18) domain, but lack the chitin-binding domain present in other GH18 enzymes. The GH18 domain of the class V chitinases has endochitinase activity in some cases and no catalytic activity in others. Included in this family is a lectin found in black locust (Robinia pseudoacacia) bark, which binds chitin but lacks chitinase activity. Also included is a chitinase-related receptor-like kinase (CHRK1) from tobacco (Nicotiana tabacum), with an N-terminal GH18 domain and a C-terminal kinase domain, which is thought to be part of a plant signaling pathway. The GH18 domain of CHRK1 is expressed extracellularly where it binds chitin but lacks chitinase activity.
Pssm-ID: 119358 [Multi-domain] Cd Length: 299 Bit Score: 168.31 E-value: 4.65e-50
The GH18 (glycosyl hydrolase, family 18) type II chitinases hydrolyze chitin, an abundant ...
24-302
6.18e-48
The GH18 (glycosyl hydrolase, family 18) type II chitinases hydrolyze chitin, an abundant polymer of beta-1,4-linked N-acetylglucosamine (GlcNAc) which is a major component of the cell wall of fungi and the exoskeleton of arthropods. Chitinases have been identified in viruses, bacteria, fungi, protozoan parasites, insects, and plants. The structure of the GH18 domain is an eight-stranded beta/alpha barrel with a pronounced active-site cleft at the C-terminal end of the beta-barrel. The GH18 family includes chitotriosidase, chitobiase, hevamine, zymocin-alpha, narbonin, SI-CLP (stabilin-1 interacting chitinase-like protein), IDGF (imaginal disc growth factor), CFLE (cortical fragment-lytic enzyme) spore hydrolase, the type III and type V plant chitinases, the endo-beta-N-acetylglucosaminidases, and the chitolectins. The GH85 (glycosyl hydrolase, family 85) ENGases (endo-beta-N-acetylglucosaminidases) are closely related to the GH18 chitinases and are included in this alignment model.
Pssm-ID: 119349 [Multi-domain] Cd Length: 210 Bit Score: 160.24 E-value: 6.18e-48
The IDGF's (imaginal disc growth factors) are a family of growth factors identified in insects ...
23-325
7.64e-37
The IDGF's (imaginal disc growth factors) are a family of growth factors identified in insects that include at least five members, some of which are encoded by genes in a tight cluster. The IDGF's have an eight-stranded alpha/beta barrel fold and are related to the glycosyl hydrolase family 18 (GH18) chitinases, but they have an amino acid substitution known to abolish chitinase catalytic activity. IDGFs may have evolved from chitinases to gain new functions as growth factors, interacting with cell surface glycoproteins involved in growth-promoting processes.
Pssm-ID: 119352 [Multi-domain] Cd Length: 413 Bit Score: 136.67 E-value: 7.64e-37
Zymocin, alpha subunit. Zymocin is a heterotrimeric enzyme that inhibits yeast cell cycle ...
23-218
2.71e-19
Zymocin, alpha subunit. Zymocin is a heterotrimeric enzyme that inhibits yeast cell cycle progression. The zymocin alpha subunit has a chitinase activity that is essential for holoenzyme action from the cell exterior while the gamma subunit contains the intracellular toxin responsible for G1 phase cell cycle arrest. The zymocin alpha and beta subunits are thought to act from the cell's exterior by docking to the cell wall-associated chitin, thus mediating gamma-toxin translocation. The alpha subunit has an eight-stranded TIM barrel fold similar to that of family 18 glycosyl hydrolases such as hevamine, chitolectin, and chitobiase.
Pssm-ID: 119357 [Multi-domain] Cd Length: 345 Bit Score: 86.98 E-value: 2.71e-19
Cortical fragment-lytic enzyme (CFLE) is a peptidoglycan hydrolase involved in bacterial ...
89-303
1.16e-12
Cortical fragment-lytic enzyme (CFLE) is a peptidoglycan hydrolase involved in bacterial endospore germination. CFLE is expressed as an inactive preprotein (called SleB) in the forespore compartment of sporulating cells. SleB translocates across the forespore inner membrane and is deposited as a mature enzyme in the cortex layer of the spore. As part of a sensory mechanism capable of initiating germination, CFLE degrades a spore-specific peptidoglycan constituent called muramic-acid delta-lactam that comprises the outer cortex. CFLE has a C-terminal glycosyl hydrolase family 18 (GH18) catalytic domain as well as two N-terminal LysM peptidoglycan-binding domains. In addition to SleB, this family includes YaaH, YdhD, and YvbX from Bacillus subtilis.
Pssm-ID: 119353 [Multi-domain] Cd Length: 313 Bit Score: 67.29 E-value: 1.16e-12
The Bacteroides thetaiotaomicron protein represented by pdb structure 3CO4 is an ...
52-302
5.40e-09
The Bacteroides thetaiotaomicron protein represented by pdb structure 3CO4 is an uncharacterized bacterial member of the family 18 glycosyl hydrolases with homologs found in Flavobacterium, Stigmatella, and Pseudomonas.
Pssm-ID: 119362 [Multi-domain] Cd Length: 253 Bit Score: 55.92 E-value: 5.40e-09
Chitobiase (also known as di-N-acetylchitobiase) is a lysosomal glycosidase that hydrolyzes ...
117-306
7.29e-06
Chitobiase (also known as di-N-acetylchitobiase) is a lysosomal glycosidase that hydrolyzes the reducing-end N-acetylglucosamine from the chitobiose core of oligosaccharides during the ordered degradation of asparagine-linked glycoproteins in eukaryotes. Chitobiase can only do so if the asparagine that joins the oligosaccharide to protein is previously removed by a glycosylasparaginase. Chitobiase is therefore the final step in the lysosomal degradation of the protein/carbohydrate linkage component of asparagine-linked glycoproteins. The catalytic domain of chitobiase is an eight-stranded alpha/beta barrel fold similar to that of other family 18 glycosyl hydrolases such as hevamine and chitotriosidase.
Pssm-ID: 119354 [Multi-domain] Cd Length: 358 Bit Score: 47.04 E-value: 7.29e-06
Stabilin-1 interacting chitinase-like protein (SI-CLP) is a eukaryotic chitinase-like protein ...
83-228
1.67e-05
Stabilin-1 interacting chitinase-like protein (SI-CLP) is a eukaryotic chitinase-like protein of unknown function that interacts with the endocytic/sorting transmembrane receptor stabilin-1 and is secreted from the lysosome. SI-CLP has a glycosyl hydrolase family 18 (GH18) domain but lacks a chitin-binding domain. The catalytic amino acids of the GH18 domain are not conserved in SI-CLP, similar to the chitolectins YKL-39, YKL-40, and YM1/2. Human SI-CLP is sorted to late endosomes and secretory lysosomes in alternatively activated macrophages.
Pssm-ID: 119355 [Multi-domain] Cd Length: 318 Bit Score: 45.76 E-value: 1.67e-05
Narbonin is a plant 2S protein from the globulin fraction of narbon bean (Vicia narbonensis L.) ...
83-171
8.69e-03
Narbonin is a plant 2S protein from the globulin fraction of narbon bean (Vicia narbonensis L.) cotyledons with unknown function. Narbonin has a glycosyl hydrolase family 18 (GH18) domain without the conserved catalytic residues and with no known enzymatic activity. Narbonin amounts to up to 3% of the total seed globulins of mature seeds and was thought to be a storage protein but was found to degrade too slowly during germination. This family also includes the VfNOD32 nodulin from Vicia faba.
Pssm-ID: 119361 Cd Length: 253 Bit Score: 37.35 E-value: 8.69e-03
Database: CDSEARCH/cdd Low complexity filter: no Composition Based Adjustment: yes E-value threshold: 0.01
References:
Wang J et al. (2023), "The conserved domain database in 2023", Nucleic Acids Res.51(D)384-8.
Lu S et al. (2020), "The conserved domain database in 2020", Nucleic Acids Res.48(D)265-8.
Marchler-Bauer A et al. (2017), "CDD/SPARCLE: functional classification of proteins via subfamily domain architectures.", Nucleic Acids Res.45(D)200-3.
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