Cyclophilin-G is a member of the peptidyl-prolyl cis-trans isomerase（PPIase) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and speeds up the protein folding. PPIG catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and is involved in the folding， transport， and assembly of proteins. PPIG is localized to the nuclear speckles， a nuclear compartment rich in splicing factors， and cooperates with the splicing factors SC35 and pinin. Cyclophilin-G also takes part in the regulation of pre-mRNA splicing.
