Structures of RPGR and its interacting proteins: RPGRIP1 and RPGRIP1L. The protein sequences of RPGRex1–19 (NP_000319.1), RPGRORF15 (NP_001030025.1), RPGRIP1 (NP_065099.3), and RPGRIP1L (NP_056087.2) were obtained from Ensembl database (http://www.ensembl.org) and domains were identified using InterPro, protein sequence analysis, classification tool (http://www.ebi.ac.uk/interpro/search/sequence-search), and details are from the literature. The isoprenylation motif (CAAX), four peptides at the N-terminal of the RPGRex1–19, is marked in yellow vertical rectangle. AD, acidic domain; BD, basic domain; C2, protein kinase C conserved domain 2; CC, coiled-coil domain; NB, GTP-binding motif; ND, nuclear domain; RID, RPGR interacting domain; RIDL, RPGR interacting domain-like.