RHODOPSIN MUTATIONS RESPONSIBLE FOR AUTOSOMAL-DOMINANT RETINITIS-PIGMENTOSA - CLUSTERING OF FUNCTIONAL CLASSES ALONG THE POLYPEPTIDE-CHAIN

Over 40 mutations in the rhodopsin gene have been identified in patien ts with autosomal dominant retinitis pigmentosa. Twenty-one of these m utations have been introduced into a human rhodopsin cDNA by site-dire cted mutagenesis, and the encoded proteins have been produced by trans fection of a human embryonic kidney cell line (293S). Three of the mut ant proteins (G51V, V345M, and P347S) resemble the wild type in yield, regenerability with 11-cis-retinal, and accumulation in the plasma me mbrane (class I). The remaining 18 mutant proteins are produced at low er levels, regenerate variably or not at all with 11-cis-retinal, and accumulate partially or predominantly in the endoplasmic reticulum (cl ass II). Together with an earlier analysis of 13 mutant rhodopsins (Su ng, C.-H., Schneider, B., Agarwal, N., Papermaster, D. S., and Nathans , J. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 8840-8844), these expe riments define distinct classes of biochemical defects in human rhodop sin and further show that amino acid substitutions in class II reside within the transmembrane and extracellular domains, whereas class I mu tants cluster in the first transmembrane domain and at the extreme car boxyl terminus.