A major RuBisCO chaperone. Acts after GroEL-GroES chaperonin to fold and/or assemble the large subunit of RuBisCO (ccbL, rbcL). Cooperates with RbcX in RbcL folding, plays the major role in assembly of dimers into RbcL(8)-Raf1(8) intermediate complexes. RbcS replaces Raf1, leading to holoenzyme formation. The Raf1 dimer brackets an RbcL dimer, leading to RbcL(8)-Raf1(8) complex formation. RbcS displaces Raf1, resulting in holoenzyme formation (PubMed:26237510, PubMed:32636267). Probably plays a role in early carboxysome assembly; in its absence CcaA, CcmM, CcmN, RbcL and RbcS colocalize in small patches while the shell proteins CcmK2, CcmK3 and CcmK4 are found diffused in the cytoplasm (PubMed:32636267). It has been suggested that Raf1 and RbcX are partially functionally redundant (Probable). Other evidence suggests they are antagonistic in mediating RuBisCO assembly (PubMed:32636267). Homodimer. Forms an RbcL(8)-Raf1(8) complex. Forms complexes of many stoichiometries with RbcL with and without RbcS. RbcX and Raf1 can bind simultaneously to RbcL. Has 3 domains, the N-terminal alpha-helical domain, an extended flexible linker and the C-terminal beta-sheet domain. The 2 C-terminal beta-sheet domains are swapped and pack against each other to form the dimer interface (By similarity). The N-terminal alpha-helical domain stabilizes RbcL dimers and dimer-dimer interactions, facilitating RbcL(8) formation. It binds to the same region of RbcL as RbcS (PubMed:32636267). The C-terminal beta-sheet domain dimerizes Raf1 (Probable) (PubMed:32636267). Decreased growth in ambient air, wild-type growth on 3% CO(2). In ambient air about 30% decreased levels of RuBisCO, decreased CO(2) fixation by whole cells. Carboxysome formation is impaired; many small, irregular electron-dense structures are present instead of the 3-4 large carboxysomes usually found in this strain, the ratio of CcmM58:CcmM35 (involved in condensing RuBisCO) rises over 3-fold. A double raf1-rbcX deletion partially recovers carboxysome formation. Belongs to the RAF family.