Conserved Protein Domain Family
CBM20_glucoamylase

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cd05811: CBM20_glucoamylase 
Click on image for an interactive view with Cn3D
Glucoamylase (glucan1,4-alpha-glucosidase), C-terminal CBM20 (carbohydrate-binding module, family 20) domain. Glucoamylases are inverting, exo-acting starch hydrolases that hydrolyze starch and related polysaccharides by releasing the nonreducing end glucose. They are mainly active on alpha-1,4-glycosidic bonds but also have some activity towards 1,6-glycosidic bonds occurring in natural oligosaccharides. The ability of glucoamylases to cleave 1-6-glycosidic binds is called "debranching activity" and is of importance in industrial applications, where complete degradation of starch to glucose is needed. Most glucoamylases are multidomain proteins containing an N-terminal catalytic domain, a C-terminal CBM20 domain, and a highly O-glycosylated linker region that connects the two. The CBM20 domain is found in a large number of starch degrading enzymes including alpha-amylase, beta-amylase, glucoamylase, and CGTase (cyclodextrin glucanotransferase). CBM20 is also present in proteins that have a regulatory role in starch metabolism in plants (e.g. alpha-amylase) or glycogen metabolism in mammals (e.g. laforin). CBM20 folds as an antiparallel beta-barrel structure with two starch binding sites. These two sites are thought to differ functionally with site 1 acting as the initial starch recognition site and site 2 involved in the specific recognition of appropriate regions of starch.
Statistics
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PSSM-Id: 99886
View PSSM: cd05811
Aligned: 32 rows
Threshold Bit Score: 127.387
Threshold Setting Gi: 116199623
Created: 10-Sep-2007
Updated: 17-Jan-2013
Structure
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Program:
Drawing:
Aligned Rows:
 
starch-bindingstarch-binding
Conserved site includes 7 residues -Click on image for an interactive view with Cn3D
Feature 1:starch-binding site 1 [chemical binding site]
Evidence:
  • Comment:Site 1 is small relative to site 2 and exhibits minimal structural changes upon ligand binding. It acts as an initial starch recognition site.
  • Structure:1AC0_A; Aspergillus niger glucoamylase CBM20 domain starch binding site 1 binds beta-cyclodextrin; defined at 4A contacts.
    View structure with Cn3D
  • Citation:PMID 9195884

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                     #    # ####                                         
1ACZ_A          1 CTtp-taVAVTFDLTATTTYGENIYLVGSISQLGDWETSDGIA-LSADKYTSSDPLWYVTVTLPaGESFEYKFIRIESd- 77
1AC0_A          1 CTtp-taVAVTFDLTATTTYGENIYLVGSISQLGDWETSDGIA-LSADKYTSSDPLWYVTVTLPaGESFEYKFIRIESd- 77
gi 119500486  526 CLsprrtVAVRFNVLATTVIGEDIFLVGSIPALGEWDARHQALkLEANEYSSITPLWYGTVMLDaGEEFEYKFIRKRVgd 605
gi 121711038  535 CTvp-taVSVTFDELAATAYGETILIVGSIPELGSWDATKAVA-LSATKYSASNPLWFVTIDLPaGKSFEYKYIRKQTn- 611
gi 146330532  509 CTpp-seVTLTFNALVDTAFGQNIYLVGSIPELGSWDPANALL-MSAKSWTSGNPVWTLSISLPaGTSFEYKFIRKDDgs 586
gi 121704316  278 CKat-gvVPVTFNVQAPTNYGENIFLVGSISQLGSWSTSSAVP-LSATQYTSSNPLWTVTVQLPaGATFEYKFIRKQKd- 354
gi 154287478  449 CVtp-dsILVTFNEVATTTLGQRIFIIGSVPELGSWDIQSAIA-LSADQYTDDNRLWHRTIQLGaGLDFEYKYLRKESge 526
gi 67903834   513 CQvp-slVSVTFELTASTVWGEEIRLVGSSGELGYWVSERGIT-FSTDRYSSSQPIWWATVWLPaGQTVEYKYIRKGEle 590
gi 461509     505 CQ-----VSITFNINATTYYGENLYVIGNSSDLGAWNIADAYP-LSASAYTQDRPLWSAAIPLNaGEVISYQYVRQEDc- 577
gi 156032806  510 CK-----YAVQFYVNATTYYGENIYVIGNTTDLGNWDLNSALP-MNAGMYTTEYPLWYVDTKLTaGDTVSYVFVRQQDc- 582
                          90       100       110
                  ....*....|....*....|....*....|....*..
Feature 1                  #                           
1ACZ_A         78 -----dSVEWESDPNREYTVPQA--CgtSTATVTDTW 107
1AC0_A         78 -----dSVEWESDPNREYTVPQA--CgtSTATVTDTW 107
gi 119500486  606 -----gKVIWEEGQNRAFVVPNE--CgpSNATINAVW 635
gi 121711038  612 -----gNVKWESNPNRSYKVPAT--CntLTDVKNDTW 641
gi 146330532  587 -----sDVVWESDPNRSYNVPKD--CgaNTATVNSWW 616
gi 121704316  355 -----gSVIWESNPNRSYTTPNG--CssSPATKTDRW 384
gi 154287478  527 svsnatSYELEGGINAIPETGNPlsQ--MDDASRRSL 561
gi 67903834   591 -----mSYLRYNNTSMLFTCWYTg-Nf-LGWTIRPWQ 620
gi 461509     578 -----dQPYIYETVNRTLTVPAC--Gg-AAVTTDDAW 606
gi 156032806  583 -----gQAPIYESGNRTVTVPECg-Tg-GTKVVRAAW 612

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