Conserved Protein Domain Family
CBM20_alpha_amylase

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cd05808: CBM20_alpha_amylase 
Alpha-amylase, C-terminal CBM20 (carbohydrate-binding module, family 20) domain. This domain is found in several bacterial and fungal alpha-amylases including the maltopentaose-forming amylases (G5-amylases). Most alpha-amylases have, in addition to the C-terminal CBM20 domain, an N-terminal catalytic domain belonging to glycosyl hydrolase family 13, which hydrolyzes internal alpha-1,4-glucosidic bonds in starch and related saccharides, yielding maltotriose and maltose. Two types of soluble substrates are used by alpha-amylases including long substrates (e.g. amylose) and short substrates (e.g. maltodextrins or maltooligosaccharides). 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: 99883
View PSSM: cd05808
Aligned: 18 rows
Threshold Bit Score: 132.103
Threshold Setting Gi: 231548
Created: 10-Sep-2007
Updated: 17-Jan-2013
Structure
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Aligned Rows:
 
starch-bindingstarch-binding
Feature 1:starch-binding site 1 [chemical binding site]
Evidence:
  • Comment:Based on the binding of substrates to the starch binding site 1 of other family members.
  • 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.
  • Citation:PMID 9195884
  • Citation:PMID 8672460

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                      #                                #           ##    
gi 113822     474 SGASFNVTa-tTVVGQNIYVTGNRAELGNWAPASALKLDPa--tYPVWKLTVGLPAGTSFEYKYIRKDaaGNVTWESGa- 549
gi 46139623   485 TTITFTVKnvqVTSGQKVYVVGSVTELSNWSPEDGIPLTEg--tEGVWSTKVKIPSDTSFEYKYIKKTssGEVTWLSDp- 561
gi 145595211  525 IATTFTVSa-tPGADQDVYAVGSISELGSWAPAAAVRLTPq--gGNTYRGTIDLPPSTAVEYKFIKVTsgGEVTWESGe- 600
gi 115378360 1357 ATVTFTVTa-sTGVGQNVYLVGNLAALGAWSPSAAIALSPa--nYPAWSVTLSLPGSTALEYKYIKKDanGNVTWESGs- 1432
gi 116503227  486 SLVTFKVYa-eTTPGENIFIAGNIGALSGWSSDNAAALSPf--eYPIWNVTLPIPVDTYFEYKYLRKDg-DSVVWEADpa 561
gi 116503128  481 AAITFRVHa-eTVWGENIFITGNIDALSGWSPDNAIPLAPt--nYPTWTATIQIPVDTNFEYKYIRKNg-NAVVWESDp- 555
gi 8468531    477 VSVTFNVDa-sTLEGQNVYLTGAVDALEDWSTDNAILLSSa--nYPTWSVTVDLPGSTDVQYKYIKKDgsGTVTWESDp- 552
gi 94966431   523 VSASVHAS---TVLGQEVRIVGSVPELGGWQPASGVALDAs--gYPSWTGGVDLPAGTSFEYKYVKVDdsGAVVWESGa- 596
gi 231548     506 VTARFHATv-tTWYGQEVAVVGSIPELGSWQPAQGVRLRTdsgtYPVWSGAVDLPAGVGFEYKYVKLN--RTAPWSGSr- 581
gi 164649511  544 AEVTFNVYa-tTQFGETIFLTGSVDALQNWSPDKALALSSa--nYPTWSVTVAVPANTNIEYKYIRKFn-GQVVWESDp- 618
                          90       100
                  ....*....|....*....|....*
Feature 1         #                        
gi 113822     550 NRTAt-VPAs-----GQLVLNDTFR 568
gi 46139623   562 NNRAl-TGSkc---gSTSTLNDEWR 582
gi 145595211  601 NRSFt-TPAs-----GTFAVTETFR 619
gi 115378360 1433 NRLYt-TPAs-----SAATLNDTWK 1451
gi 116503227  562 RRNNsiSPDg-----ESKTINDVWR 581
gi 116503128  556 NRRNs-SPSs-----GSKTINDSWK 574
gi 8468531    553 NMEIt-TPAn-----GTYATNDTWR 571
gi 94966431   597 NRTAt-VGAd-----GTLALNDTWR 615
gi 231548     582 AATAs-PPWmtsgggCSQNFYDSWR 605
gi 164649511  619 NNAFt-SPGs----gQSVTLGDTWR 638

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