ID   RBS_ANTSP               Reviewed;         138 AA.
AC   P25458;
DT   01-MAY-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1992, sequence version 1.
DT   25-MAY-2022, entry version 95.
DE   RecName: Full=Ribulose bisphosphate carboxylase small subunit {ECO:0000255|HAMAP-Rule:MF_00859};
DE            Short=RuBisCO small subunit {ECO:0000255|HAMAP-Rule:MF_00859};
GN   Name=rbcS {ECO:0000255|HAMAP-Rule:MF_00859};
OS   Antithamnion sp. (Red alga).
OG   Plastid; Chloroplast.
OC   Eukaryota; Rhodophyta; Florideophyceae; Rhodymeniophycidae; Ceramiales;
OC   Ceramiaceae; Antithamnion; unclassified Antithamnion.
OX   NCBI_TaxID=2767;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2078870; DOI=10.1007/bf00309918;
RA   Kostrzewa M., Valentin K.-U., Maid U., Radetzky R., Zetsche K.;
RT   "Structure of the rubisco operon from the multicellular red alga
RT   Antithamnion spec.";
RL   Curr. Genet. 18:465-469(1990).
CC   -!- FUNCTION: RuBisCO catalyzes two reactions: the carboxylation of D-
CC       ribulose 1,5-bisphosphate, the primary event in carbon dioxide
CC       fixation, as well as the oxidative fragmentation of the pentose
CC       substrate in the photorespiration process. Both reactions occur
CC       simultaneously and in competition at the same active site. Although the
CC       small subunit is not catalytic it is essential for maximal activity.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SUBUNIT: Heterohexadecamer of 8 large and 8 small subunits.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast {ECO:0000255|HAMAP-
CC       Rule:MF_00859}.
CC   -!- MISCELLANEOUS: In this alga, in contrast to plants, the small subunit
CC       is encoded in the chloroplast.
CC   -!- MISCELLANEOUS: The basic functional RuBisCO is composed of a large
CC       chain homodimer in a 'head-to-tail' conformation. In form I RuBisCO
CC       this homodimer is arranged in a barrel-like tetramer with the small
CC       subunits forming a tetrameric 'cap' on each end of the 'barrel'.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
CC   -!- SIMILARITY: Belongs to the RuBisCO small chain family.
CC       {ECO:0000255|HAMAP-Rule:MF_00859}.
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DR   EMBL; X54532; CAA38399.1; -; Genomic_DNA.
DR   PIR; S14155; RKKKSA.
DR   AlphaFoldDB; P25458; -.
DR   SMR; P25458; -.
DR   GO; GO:0009507; C:chloroplast; IEA:UniProtKB-SubCell.
DR   GO; GO:0019253; P:reductive pentose-phosphate cycle; IEA:UniProtKB-KW.
DR   CDD; cd03527; RuBisCO_small; 1.
DR   Gene3D; 3.30.190.10; -; 1.
DR   HAMAP; MF_00859; RuBisCO_S_bact; 1.
DR   InterPro; IPR024681; RuBisCO_ssu.
DR   InterPro; IPR000894; RuBisCO_ssu_dom.
DR   InterPro; IPR036385; RuBisCO_ssu_sf.
DR   PANTHER; PTHR31262; PTHR31262; 1.
DR   Pfam; PF00101; RuBisCO_small; 1.
DR   SMART; SM00961; RuBisCO_small; 1.
DR   SUPFAM; SSF55239; SSF55239; 1.
PE   3: Inferred from homology;
KW   Calvin cycle; Carbon dioxide fixation; Chloroplast; Photorespiration;
KW   Photosynthesis; Plastid.
FT   CHAIN           1..138
FT                   /note="Ribulose bisphosphate carboxylase small subunit"
FT                   /id="PRO_0000198591"
SQ   SEQUENCE   138 AA;  16143 MW;  361857D68BF0F48F CRC64;
     MRLTQGTFSF LPDLTDEQIK KQIAYAVSQN WAINIEFTDD PHPRNNYWEL WGLPLFDIND
     VESVMYELES CRKQHSGLYI KINAFDNTRG VESCVLSFII NRPSYEPGFE LIRSEDIGRN
     QKYSFRSYAT AKPEGSRY