ID   RBS_GUITH               Reviewed;         139 AA.
AC   P14960;
DT   01-APR-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1990, sequence version 1.
DT   25-MAY-2022, entry version 123.
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   Guillardia theta (Cryptophyte) (Cryptomonas phi).
OG   Plastid; Chloroplast.
OC   Eukaryota; Cryptophyceae; Pyrenomonadales; Geminigeraceae; Guillardia.
OX   NCBI_TaxID=55529;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2562756; DOI=10.1007/bf00027331;
RA   Douglas S.E., Durnford D.G.;
RT   "The small subunit of ribulose-1,5-bisphosphate carboxylase is plastid-
RT   encoded in the chlorophyll c-containing alga Cryptomonas phi.";
RL   Plant Mol. Biol. 13:13-20(1989).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-46.
RA   Douglas S.E., Durnford D.G., Morden C.W.;
RT   "Nucleotide sequence of the gene for the large subunit of ribulose-1,5-
RT   bisphosphate carboxylase/oxygenase from Cryptomonas phi: evidence
RT   supporting the polyphyletic origin of plastids.";
RL   J. Phycol. 26:500-508(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; AF041468; AAC35640.1; -; Genomic_DNA.
DR   RefSeq; NP_050706.1; NC_000926.1.
DR   AlphaFoldDB; P14960; -.
DR   SMR; P14960; -.
DR   GeneID; 857004; -.
DR   HOGENOM; CLU_098114_2_0_1; -.
DR   OMA; KQCQVLS; -.
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..139
FT                   /note="Ribulose bisphosphate carboxylase small subunit"
FT                   /id="PRO_0000198599"
SQ   SEQUENCE   139 AA;  15984 MW;  85B696CD99275774 CRC64;
     MRLTQGAFSF LPDLTDEQIV KQIQYAISKN WALNVEWTDD PHPRNAYWDL WGLPLFGIKD
     PAAVMFEINA CRKAKPACYV KVNAFDNSRG VESCCLSFIV QRPTSNEPGF QLIRSEVDSR
     NIRYTIQSYA STRPEGERY