PROSITE documentation PDOC00544

Regulator of chromosome condensation (RCC1) signatures and profile

The regulator of chromosome condensation (RCC1) [1] is a eukaryotic protein which binds to chromatin and interacts with ran, a nuclear GTP-binding protein (see <PDOC00859>), to promote the loss of bound GDP and the uptake of fresh GTP, thus acting as a guanine-nucleotide dissociation stimulator (GDS) [2]. The interaction of RCC1 with ran probably plays an important role in the regulation of gene expression.

RCC1, known as PRP20 or SRM1 in yeast, pim1 in fission yeast and BJ1 in Drosophila, is a protein that contains seven tandem repeats of a domain of about 50 to 60 amino acids. As shown in the following schematic representation, the repeats make up the major part of the length of the protein. Outside the repeat region, there is just a small N-terminal domain of about 40 to 50 residues and, in the Drosophila protein only, a C-terminal domain of about 130 residues.

  +----+-------+-------+-------+-------+-------+-------+-------+-------------+
  |N-t.|Rpt. 1 |Rpt. 2 |Rpt. 3 |Rpt. 4 |Rpt. 5 |Rpt. 6 |Rpt. 7 | C-terminal  |
  +----+-------+-------+-------+-------+-------+-------+-------+-------------+
                                                                 In Drosophila

RCC1 repeats are also found in the following proteins:

• Mammalian retinitis pigmentosa GTPase regulator (RPGR) [3]. Mutations in the RPGR gene cause X-linked retinitis pigmentosa type 3 (RP3), a severe, progressive and degenerative retinal dystrophy eventually leading to complete blindness.
• Mammalian HERC2 protein. A putative guanine nucleotide exchange factor that could be involved in protein trafficking.

We developed two signature patterns for RCC1. The first is found in the N-terminal part of the second repeat; this is the most conserved part of RCC1. The second is derived from conserved positions in the C-terminal part of each repeat and detects up to five copies of the repeated domain. We also developed a profile that covers the whole repeat.