ID   RBS4_ACEAT              Reviewed;         182 AA.
AC   P16137;
DT   01-APR-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1990, sequence version 1.
DT   25-MAY-2022, entry version 95.
DE   RecName: Full=Ribulose bisphosphate carboxylase small subunit, chloroplastic 4 {ECO:0000255|HAMAP-Rule:MF_00860};
DE            Short=RuBisCO small subunit 4 {ECO:0000255|HAMAP-Rule:MF_00860};
DE   Flags: Precursor;
GN   Name=RBCS4 {ECO:0000255|HAMAP-Rule:MF_00860}; Synonyms=RBCS-4;
OS   Acetabularia acetabulum (Mermaid's wine glass) (Acetabularia mediterranea).
OC   Eukaryota; Viridiplantae; Chlorophyta; Ulvophyceae; TCBD clade;
OC   Dasycladales; Polyphysaceae; Acetabularia.
OX   NCBI_TaxID=35845;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=17;
RX   PubMed=2573818; DOI=10.1007/bf00332408;
RA   Schneider S.U., Leible M.B., Yang X.P.;
RT   "Strong homology between the small subunit of ribulose-1,5-bisphosphate
RT   carboxylase/oxygenase of two species of Acetabularia and the occurrence of
RT   unusual codon usage.";
RL   Mol. Gen. Genet. 218:445-452(1989).
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. Both reactions occur simultaneously and in competition at
CC       the same active site. Although the small subunit is not catalytic it is
CC       essential for maximal activity. {ECO:0000255|HAMAP-Rule:MF_00860}.
CC   -!- SUBUNIT: Heterohexadecamer of 8 large and 8 small subunits.
CC       {ECO:0000255|HAMAP-Rule:MF_00860}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast {ECO:0000255|HAMAP-
CC       Rule:MF_00860}.
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_00860}.
CC   -!- SIMILARITY: Belongs to the RuBisCO small chain family.
CC       {ECO:0000255|HAMAP-Rule:MF_00860}.
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DR   EMBL; X51814; CAA36111.1; -; mRNA.
DR   PIR; S05350; RKJK4M.
DR   AlphaFoldDB; P16137; -.
DR   SMR; P16137; -.
DR   PRIDE; P16137; -.
DR   GO; GO:0009507; C:chloroplast; IEA:UniProtKB-SubCell.
DR   GO; GO:0009853; P:photorespiration; IEA:UniProtKB-KW.
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   PRINTS; PR00152; RUBISCOSMALL.
DR   SMART; SM00961; RuBisCO_small; 1.
DR   SUPFAM; SSF55239; SSF55239; 1.
PE   2: Evidence at transcript level;
KW   Calvin cycle; Carbon dioxide fixation; Chloroplast; Photorespiration;
KW   Photosynthesis; Plastid; Transit peptide.
FT   TRANSIT         1..41
FT                   /note="Chloroplast"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00860"
FT   CHAIN           42..182
FT                   /note="Ribulose bisphosphate carboxylase small subunit,
FT                   chloroplastic 4"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00860"
FT                   /id="PRO_0000031457"
SQ   SEQUENCE   182 AA;  20534 MW;  17E401AF3172BEF6 CRC64;
     MSAAMMNKSV VLSKQCTKPA ATPKVVTSKR SFASTVANKN REMMVWQPFN NKMFETFSFL
     PPLTDEQISK QVDYILANSW TPCLEFAASD QAYAGNENCI RMGPVASTYQ DNRYWTMWKL
     PMFGCTDGSQ VLSEIQACTN AFPDAYIRLV CFDANRQVQI SGFLVHRPPS ATDYRLPADR
     QV