P 371 Cytogenetic studies in retinitis pigmentosa patients

The retina contains due families of phspbolipnsc C (P, 6. and u). a reccctor-activated ewYmC that PFeratcs two iolraceUuhv s%xmd n&cngcrs, diacylgly&ol md I ,$5-inositol rrispbospbale. We hnvc charactaizcd the cDNA and par&d gene sh-ucnue for human PLCB4, a p isofurm which shares uighcsr sequence homology with dx norpA PLC from Drosophila. A muwion in tie nor@ PU: leads m I retinal demmtioo m dte flv. Immunobtot and immunowtocbem~cal analyses w&c carried au, onbovioc, monkey, “d huti mhlv and reti& membranes with a pcptidc-specific antitidies (Ab) 0 d~c C-tznniou~ of bovioe PLCp4. hnmuwbtot analysi of whole human rctioa membranes shvcd, 130 kDa immonorcactivc protein and a less abundmt 150-160 kDa pmtcin hnmwhesninl &ia showed immunoreacdon in tic photmxquor cell bya md the outa plcxifoml mu layer of bovine rctbu The compositccDNA xquenec derived from several overtapping cDNA &,,us &,,rh,,w,,, dnd Library predicis a hunus PLCp4 polypeplidc of ,022 amino acid residues (mw. I17.000). Illis PLQ34 variant tacks P 165 mdno ,&I N-tcrminnl domiC chvactaistic for the mt bhin imro,m, but bz,s , disdnc, putivc cxon I “niqw for bun= and bovine mdm iwfomu. Humps gcnomic DNA ws mqdifed witi cxoo specific primers to map intxonlcxon juncdon8. The I34 gme conti yl ioUOOLess purativc cxon t hagmcnt mntihg PI and the lranstatioo EM codon. I,, addition exon 2 (95 bp) and cxoo 3 (58 bp), IS well IS invon 1 (I kb) u,d iomn h (0.6 kb) bwe hem wped. Exon 3 ~rrcyponds to Ox P3 slice varianr. Somatic cell hybrids. and d&lion panels were used u, bmlizc Ihe m34 gco~ IO die &orI arm of chromosome 20. ‘The gcnc was 6mbcr sublocalized (0 20~12 by fluOrc~cco~e in situ hybridndon.