ID   AMY4_HORVU              Reviewed;         153 AA.
AC   P04748;
DT   13-AUG-1987, integrated into UniProtKB/Swiss-Prot.
DT   13-AUG-1987, sequence version 1.
DT   02-SEP-2026, entry version 122.
DE   RecName: Full=Alpha-amylase type B isozyme;
DE            EC=3.2.1.1 {ECO:0000250|UniProtKB:P00693};
DE   AltName: Full=1,4-alpha-D-glucan glucanohydrolase;
DE   AltName: Full=Clone 103;
DE   Flags: Fragment;
GN   Name=AMY1.4;
OS   Hordeum vulgare (Barley).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; Liliopsida; Poales; Poaceae; BOP clade;
OC   Pooideae; Triticodae; Triticeae; Hordeinae; Hordeum.
OX   NCBI_TaxID=4513;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=6335720;
RA   Huang J.-K., Swegle M., Dandekar A.M., Muthukrishnan S.;
RT   "Expression and regulation of alpha-amylase gene family in barley
RT   aleurones.";
RL   J. Mol. Appl. Genet. 2:579-588(1984).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in
CC         polysaccharides containing three or more (1->4)-alpha-linked D-
CC         glucose units.; EC=3.2.1.1; Evidence={ECO:0000250|UniProtKB:P00693};
CC   -!- COFACTOR:
CC       Name=Ca(2+); Xref=ChEBI:CHEBI:29108;
CC         Evidence={ECO:0000250|UniProtKB:P00693};
CC       Note=Binds 3 Ca(2+) ions per subunit. {ECO:0000250|UniProtKB:P00693};
CC   -!- SUBUNIT: Monomer. {ECO:0000250}.
CC   -!- DEVELOPMENTAL STAGE: Production of alpha-amylase is hormonally
CC       regulated. Germinating embryos produce the hormone gibberellic acid,
CC       which within 10 hours stimulates the aleurone cells covering the
CC       endosperm of the seed to produce alpha-amylase. The enzyme then
CC       degrades the starch within the endosperm for use by the developing
CC       plant embryo.
CC   -!- MISCELLANEOUS: There are at least 4 types of alpha-amylase in barley.
CC   -!- MISCELLANEOUS: Type B isozyme mRNA is undetectable in unstimulated
CC       cells and increases a hundred-fold after stimulation with gibberellic
CC       acid.
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 13 family. {ECO:0000305}.
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DR   EMBL; M10056; AAA32930.1; -; mRNA.
DR   PIR; A21826; A21826.
DR   AlphaFoldDB; P04748; -.
DR   SMR; P04748; -.
DR   GO; GO:0004556; F:alpha-amylase activity; ISS:UniProtKB.
DR   GO; GO:0005509; F:calcium ion binding; IEA:InterPro.
DR   GO; GO:0005983; P:starch catabolic process; IEA:UniProtKB-ARBA.
DR   GO; GO:0005987; P:sucrose catabolic process; IEA:UniProtKB-ARBA.
DR   FunFam; 2.60.40.1180:FF:000021; Alpha-amylase; 1.
DR   Gene3D; 3.20.20.80; Glycosidases; 1.
DR   Gene3D; 2.60.40.1180; Golgi alpha-mannosidase II; 1.
DR   InterPro; IPR012850; A-amylase_bs_C.
DR   InterPro; IPR017853; GH_hydrolase_sf.
DR   InterPro; IPR013780; Glyco_hydro_b.
DR   PANTHER; PTHR43447; ALPHA-AMYLASE; 1.
DR   Pfam; PF07821; Alpha-amyl_C2; 1.
DR   SMART; SM00810; Alpha-amyl_C2; 1.
DR   SUPFAM; SSF51445; (Trans)glycosidases; 1.
DR   SUPFAM; SSF51011; Glycosyl hydrolase domain; 1.
PE   2: Evidence at transcript level;
KW   Calcium; Carbohydrate metabolism; Germination; Glycosidase; Hydrolase.
FT   CHAIN           <1..153
FT                   /note="Alpha-amylase type B isozyme"
FT                   /id="PRO_0000054292"
FT   BINDING         19
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   BINDING         25..27
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P04063"
FT   BINDING         38
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   BINDING         44
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   BINDING         123
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   BINDING         150
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   SITE            39
FT                   /note="Transition state stabilizer"
FT                   /evidence="ECO:0000250|UniProtKB:P00693"
FT   NON_TER         1
SQ   SEQUENCE   153 AA;  17276 MW;  BE5233AE1D265F72 CRC64;
     ILNVAVEGAL WRLRGTDGKA PSMIGWWPAK AVTFVDNHDT GSTQHMWPFP SDRVMQGYAY
     ILTHPRTPCI FYDHFFDWGP KEEIDRLVSV RTRHGIHNES KLQIIEADAD LYLAEIDGKV
     IVKLGPRYDV GNLIPGGFEG AAHGNDYAVW EKI
//