Rab geranylgeranyl transferase (RabGGT) catalyses the addition of two geranylgeranyl groups to the C-terminal cysteine residues of Rab proteins, which is crucial for membrane association and function of these proteins in intracellular vesicular trafficking [1]. This domain is inserted between Pfam:PF01239 repeats. This domain adopts an Ig-like fold and is thought to be involved in protein-protein interactions and might be involved in the recognition and binding of REP [1].

1: Crystal structure of Rab geranylgeranyltransferase at 2.0 A resolution. Zhang H, Seabra MC, Deisenhofer J; Structure Fold Des 2000;8:241-251. PMID:10745007