The human photoreceptor rim protein gene ( ABCR ): genomic structure and primer set information for mutation analysis

Rim protein (RmP) is an integral membrane glycoprotein localized to the rims of photoreceptor outer-segment discs. It belongs to the ABC transporter superfamily, but its function in the retina has not been determined. The gene for human RmP ( ABCR ) is affected in several recessively inherited human retinal degenerations, including Stargardt’s macular dystrophy, retinitis pigmentosa, and cone-rod dystrophy. The complete structure of ABCR has not been determined. Here, we report the cloning of the human ABCR gene and present its complete intron-exon structure. The gene contains 50 exons that range in size from 33 to 406 bp. Almost all of the splice junctions follow the AG/GT rule. We have identified the site of transcription initiation by 5′ RACE. The first several hundred bases upstream of the transcription unit are relatively conserved between mouse and human and contain several predicted cis -regulatory elements including a TATA-like box at –27 bp, and two Ret-4-like elements that reportedly confer photoreceptor-specific gene expression. We also present a complete set of tested oligonucleotide primers for the amplification and analysis of exons 1–50 by the polymerase chain reaction. These data should help with the identification of new disease-causing mutations in ABCR .