ID   ILVH_PORPU              Reviewed;         174 AA.
AC   P51230;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   25-MAY-2022, entry version 82.
DE   RecName: Full=Acetolactate synthase small subunit;
DE            EC=2.2.1.6;
DE   AltName: Full=Acetohydroxy-acid synthase small subunit;
DE            Short=AHAS;
DE            Short=ALS;
GN   Name=ilvH;
OS   Porphyra purpurea (Red seaweed) (Ulva purpurea).
OG   Plastid; Chloroplast.
OC   Eukaryota; Rhodophyta; Bangiophyceae; Bangiales; Bangiaceae; Porphyra.
OX   NCBI_TaxID=2787;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Avonport;
RA   Reith M.E., Munholland J.;
RT   "Complete nucleotide sequence of the Porphyra purpurea chloroplast
RT   genome.";
RL   Plant Mol. Biol. Rep. 13:333-335(1995).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H(+) + 2 pyruvate = (2S)-2-acetolactate + CO2;
CC         Xref=Rhea:RHEA:25249, ChEBI:CHEBI:15361, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:16526, ChEBI:CHEBI:58476; EC=2.2.1.6;
CC   -!- PATHWAY: Amino-acid biosynthesis; L-isoleucine biosynthesis; L-
CC       isoleucine from 2-oxobutanoate: step 1/4.
CC   -!- PATHWAY: Amino-acid biosynthesis; L-valine biosynthesis; L-valine from
CC       pyruvate: step 1/4.
CC   -!- SUBUNIT: Dimer of large and small chains. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast.
CC   -!- SIMILARITY: Belongs to the acetolactate synthase small subunit family.
CC       {ECO:0000305}.
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DR   EMBL; U38804; AAC08116.1; -; Genomic_DNA.
DR   PIR; S73151; S73151.
DR   RefSeq; NP_053840.1; NC_000925.1.
DR   AlphaFoldDB; P51230; -.
DR   SMR; P51230; -.
DR   GeneID; 809858; -.
DR   UniPathway; UPA00047; UER00055.
DR   UniPathway; UPA00049; UER00059.
DR   GO; GO:0009507; C:chloroplast; IEA:UniProtKB-SubCell.
DR   GO; GO:0003984; F:acetolactate synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:1990610; F:acetolactate synthase regulator activity; IEA:InterPro.
DR   GO; GO:0009097; P:isoleucine biosynthetic process; IEA:UniProtKB-UniPathway.
DR   GO; GO:0009099; P:valine biosynthetic process; IEA:UniProtKB-UniPathway.
DR   CDD; cd04878; ACT_AHAS; 1.
DR   Gene3D; 3.30.70.1150; -; 1.
DR   InterPro; IPR004789; Acetalactate_synth_ssu.
DR   InterPro; IPR027271; Acetolactate_synth/TF_NikR_C.
DR   InterPro; IPR019455; Acetolactate_synth_ssu_C.
DR   InterPro; IPR045865; ACT-like_dom_sf.
DR   InterPro; IPR002912; ACT_dom.
DR   InterPro; IPR039557; AHAS_ACT.
DR   PANTHER; PTHR30239; PTHR30239; 1.
DR   Pfam; PF10369; ALS_ss_C; 1.
DR   SUPFAM; SSF55021; SSF55021; 2.
DR   TIGRFAMs; TIGR00119; acolac_sm; 1.
DR   PROSITE; PS51671; ACT; 1.
PE   3: Inferred from homology;
KW   Amino-acid biosynthesis; Branched-chain amino acid biosynthesis;
KW   Chloroplast; Plastid; Transferase.
FT   CHAIN           1..174
FT                   /note="Acetolactate synthase small subunit"
FT                   /id="PRO_0000151428"
FT   DOMAIN          4..78
FT                   /note="ACT"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01007"
SQ   SEQUENCE   174 AA;  19253 MW;  53989280EA3D5C5F CRC64;
     MKHTLSVLVQ DEAGVLSRIS GLFARRGFNI ASLAVGPAEQ IGVSRITMVV QGDNRTIEQL
     TKQLYKLVNI LNVQDVTNIP SVERELMLIK IQVNSQNRIE ALEIVKIFRA NVVDIAEDLI
     IVEVTGDPGK IVAIEQLLTK FGIIEIARTG KISLVRTSKI NTEYLKDKVV AYNA