Ribulose bisphosphate carboxylase large subunit, type I (IPR020888)

Short name: RuBisCO_lsuI

Overlapping homologous superfamilies

Family relationships

  • RuBisCO (IPR033966)
    • Ribulose bisphosphate carboxylase large subunit, type I (IPR020888)


Ribulose bisphosphate carboxylase (RuBisCO) [PMID: 6351728, PMID: 12221984] catalyses the initial step in Calvin's reductive pentose phosphate cycle in plants as well as purple and green bacteria. It catalyzes the primary CO2 fixation step. RuBisCO consists of a large catalytic unit and a small subunit of undetermined function. In plants, the large subunit is coded by the chloroplastic genome while the small subunit is encoded in the nuclear genome. Rubisco is activated by carbamylation of an active site lysine, stabilized by a divalent cation, which then catalyzes the proton abstraction from the substrate ribulose 1,5 bisphosphate (RuBP) and leads to the formation of two molecules of 3-phosphoglycerate [PMID: 1969412, PMID: 9034362].

Members of the Rubisco family can be divided into 4 subgroups, form I-IV , which differ in their taxonomic distribution and subunit composition [PMID: 18281717, PMID: 18063718]. Form I is the most abundant class, present in plants, algae, and bacteria, and forms large complexes composed of 8 large and 8 small subunits.

GO terms

Biological Process

GO:0015977 carbon fixation

Molecular Function

GO:0000287 magnesium ion binding
GO:0016984 ribulose-bisphosphate carboxylase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.