The RCC1 superfamily: From genes, to function, to disease

The Regulator of Chromosome Condensation 1 (RCC1) was identified over 20  years ago as a critical cell cycle regulator. By analyzing its amino acid sequence, RCC1 was found to consist of seven homologous repeats of 51–68 amino acid residues, which were later shown to adopt a seven-bladed β-propeller fold. Since the initial identification of RCC1, a number of proteins have been discovered that contain one or more RCC1-like domains (RLDs). As we show here, these RCC1 superfamily proteins can be subdivided in five subgroups based on structural criteria. In recent years, a number of studies have been published regarding the functions of RCC1 superfamily proteins. From these studies, the emerging picture is that the RLD is a versatile domain which may perform many different functions, including guanine nucleotide exchange on small GTP-binding proteins, enzyme inhibition or interaction with proteins and lipids. Here, we review the available structural and functional data on RCC1 superfamily members, paying special attention to the human proteins and their involvement in disease.