Retinitis Pigmentosa GTPase Regulator (RPGR) protein isoforms in mammalian retina: insights into X-linked Retinitis Pigmentosa and associated ciliopathies.
Mutations in the cilia-centrosomal protein Retinitis Pigmentosa GTPase Regulator (RPGR) are a frequent cause of retinal degeneration. The RPGR gene undergoes complex alternative splicing and encodes multiple protein isoforms. To elucidate the function of major RPGR isoforms (RPGR 1-19 and RPGR ORF15), we have generated isoform-specific antibodies and examined their expression and localization in the retina. Using sucrose-gradient centrifugation, immunofluorescence and co-immunoprecipitation methods, we show that RPGR isoforms localize to distinct sub-cellular compartments in mammalian photoreceptors and associate with a number of cilia-centrosomal proteins. The RCC1-like domain of RPGR, which is present in all major RPGR isoforms, is sufficient to target it to the cilia and centrosomes in cultured cells. Our findings indicate that multiple isotypes of RPGR may perform overlapping yet somewhat distinct transport-related functions in photoreceptors.
He
Shirley
S
Department of Ophthalmology and Visual Sciences, University of Michigan, W. K. Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI 48105, USA.
Parapuram
Sunil K
SK
Hurd
Toby W
TW
Behnam
Babak
B
Margolis
Ben
B
Swaroop
Anand
A
Khanna
Hemant
H
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D002417:Cattle; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D018385:Centrosome / Q000378:metabolism; D015785:Eye Diseases, Hereditary / Q000235:genetics* / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D040181:Genetic Diseases, X-Linked / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism / Q000502:physiology; D012160:Retina / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000235:genetics* / Q000378:metabolism; D013045:Species Specificity
D002352:Carrier Proteins; D005136:Eye Proteins; D020033:Protein Isoforms; C513598:RPGR protein, mouse